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Summer in Japan brings a particular craving that has persisted for centuries. When temperatures soar and humidity weighs heavy, people across the country seek out unagi, believing this rich, glazed eel provides stamina to endure the sweltering season.
Unagi represents one of Japanese cuisine’s cherished luxuries. These freshwater eels undergo a transformation through patient grilling and basting, emerging with lacquered skin and flesh that melts on your tongue. The preparation demands skill that takes years to master.
You’ll find unagi restaurants, called unagi-ya, throughout Japan, some family run establishments continuing techniques passed down through generations. The aroma of grilling eel and caramelising sauce wafts through their doorways, drawing devoted followers who return year after year.
This dish holds cultural significance beyond mere sustenance. It appears during particular seasons and celebrations, connecting modern diners to traditions that stretch back centuries. Each bite carries the weight of culinary heritage and the dedication of craftspeople who honour their trade.
Want to dive deeper into Japanese Cuisine? Don’t miss our post on 26 Traditional Japanese Foods to Try
What Is Unagi?
Unagi refers specifically to freshwater eel, particularly the Japanese eel species Anguilla japonica. The preparation involves butterflying the eel, removing bones, skewering it flat, and grilling it over charcoal whilst repeatedly basting with a sweet soy-based glaze called tare.
The cooking process follows precise stages. First, the eel gets grilled without sauce to render some of its natural oils and firm the flesh. Then it receives multiple coatings of tare between brief stints over the flames, building layers of flavour and creating that distinctive glossy finish.
Regional variations exist in how the eel gets prepared. In Tokyo and eastern Japan, chefs steam the eel before final grilling, producing softer, more delicate flesh. Osaka and western regions skip steaming, preferring direct grilling that yields a slightly firmer texture with crispier edges.
The presentation matters greatly. Unagi typically arrives atop a lacquered box of steamed rice, called unaju, or in a ceramic bowl as unadon. Some restaurants serve it with just rice and sauce, whilst others add pickles, clear soup, and powdered sansho pepper.
Proper unagi should show char marks from the grill without being burnt. The skin develops a pleasant chewiness whilst the interior remains tender. The glaze should taste balanced, sweet but not cloying, with savoury depth that complements rather than overwhelms the eel’s natural richness.
Ingredients and Taste
The ingredient list appears deceptively simple. Fresh eel forms the foundation, though sourcing quality specimens has become increasingly challenging. The tare sauce combines soy sauce, mirin, sake, and sugar, with each restaurant guarding its particular ratio and often maintaining the same sauce base for decades.
Master unagi chefs add drippings from grilled eel back into their tare, creating a sauce that deepens in complexity over time. Some establishments proudly serve sauce that’s been continuously replenished for generations, carrying flavours that span decades of cooking.
Sansho pepper, made from ground Japanese prickly ash berries, traditionally accompanies unagi. This isn’t hot like black pepper but offers a unique tingling sensation and citrusy aroma that cuts through the eel’s fattiness beautifully.
The taste experience proves difficult to compare to anything else. Unagi possesses a rich, almost buttery quality with subtle sweetness from its natural oils. The flesh feels simultaneously delicate and substantial, flaking easily yet maintaining satisfying texture.
That tare glaze brings umami intensity, melding salty, sweet, and savoury elements into something that makes plain rice suddenly compelling. Each grain soaks up the sauce that drips from the eel, transforming humble ingredients into something luxurious.
The charcoal grilling imparts a subtle smokiness that threads through everything. It’s never aggressive but adds dimension that distinguishes restaurant unagi from versions cooked on standard grills. The contrast between caramelised edges and tender interior creates textural interest throughout.
A Taste of History
Eel consumption in Japan dates back over a thousand years. Ancient texts mention eels as food, though early preparations differed vastly from today’s glazed and grilled versions. People initially consumed eel more simply, often just salted or perhaps grilled without elaborate sauces.
The sweet soy glaze that defines modern unagi emerged during the Edo period, roughly the 17th to 19th centuries. This era saw Tokyo, then called Edo, develop into a thriving urban centre where quick, flavourful foods gained popularity among busy city dwellers.
Street vendors began offering grilled eel, developing techniques to make this somewhat bony, strong flavoured fish appealing to wider audiences. The steaming method that characterises Kanto style unagi likely developed during this period, addressing complaints about toughness and bones.
A custom called doyo no ushi no ushi emerged, designating specific summer days when eating unagi supposedly provided strength and vitality. This tradition, promoted by clever marketing in the 18th century, continues today with restaurants experiencing their busiest periods during these dates.
The post war period saw unagi transform from everyday fare to luxury item. Eel populations declined whilst demand remained strong, driving prices upward. What once sustained common workers became special occasion food, though its cultural importance never diminished.
Today, unagi faces sustainability concerns. Wild eel populations have plummeted dramatically, leading to aquaculture efforts and searches for alternatives. Yet the dish remains deeply woven into Japanese food culture, with ongoing efforts to preserve both the tradition and the species.
How to Make Unagi (Grilled Eel)
Unagi, or grilled freshwater eel, is a cherished Japanese delicacy known for its rich, smoky aroma and perfectly balanced sweet savoury glaze. The process requires patience and precision, resulting in tender, flavourful eel with caramelised skin that melts in the mouth. See the recipe card at the bottom for printable directions
Ingredients
- 4 fillets fresh unagi (freshwater eel), cleaned and deboned
- 2 tbsp sake
- 2 tbsp mirin
- 2 tbsp soy sauce
- 1 tbsp sugar
- 1 tbsp water
- 1 tsp vegetable oil (for grilling)
- Steamed short-grain rice, to serve
- Sansho pepper (optional, for garnish)
Cooking Instructions
Step 1: Prepare the Unagi Sauce (Tare)
In a small saucepan, combine soy sauce, mirin, sake, sugar, and water. Place over medium heat and stir until the sugar dissolves completely. Allow the sauce to simmer gently for about 10 minutes until slightly thickened. Remove from the heat and set aside to cool.
Step 2: Prepare the Grill
Preheat a charcoal grill or grill pan to medium heat. Lightly brush the grill with vegetable oil to prevent sticking. A traditional Japanese unagi grill imparts a delicate smokiness that defines the dish.
Step 3: Steam the Eel (Optional Step for Tenderness)
Place the eel fillets in a bamboo steamer or over a heatproof plate and steam for 5–7 minutes. This step softens the flesh and reduces excess oil, ensuring a smooth, melt in the mouth texture before grilling.
Step 4: First Grilling
Lay the steamed eel skin side down on the grill. Cook for 5–6 minutes until the surface begins to brown lightly. Avoid moving the eel too much to prevent it from breaking apart.
Step 5: Apply the First Glaze
Brush the eel generously with the tare sauce, then flip carefully using tongs or a wide spatula. Brush the other side and continue grilling for another 3–4 minutes. The sugar in the sauce will begin to caramelise beautifully.
Step 6: Repeat Glazing and Grilling
Continue brushing and grilling the eel for another 5–7 minutes, turning occasionally. Each layer of glaze deepens the flavour and adds shine. The goal is a glossy, lacquered surface with lightly crisped edges.
Step 7: Prepare the Rice Base
While the eel finishes cooking, portion freshly steamed rice into four bowls. Keep the rice warm and slightly firm, as it complements the rich sauce of the eel perfectly.
Step 8: Final Glaze and Resting
Give the eel a final brush of sauce just before removing it from the grill. Allow it to rest for 2 minutes to let the juices settle and the glaze set evenly.
Step 9: Slice for Serving
Using a sharp knife, cut the eel fillets into neat portions. Traditionally, they are sliced diagonally for elegant presentation and easy eating.
Step 10: Serve the Unagi Donburi
Lay the eel slices over bowls of rice and drizzle lightly with extra sauce. Sprinkle with a pinch of sansho pepper if desired. Serve immediately while hot, accompanied by pickles or miso soup for a complete meal.
Variations and Substitutions
- Unagi substitute: If fresh eel is unavailable, use sea eel (anago) or even grilled mackerel for a similar texture.
- Sauce substitute: Pre-made unagi tare sauce is available in Japanese grocers and can replace the homemade version.
- Cooking method: For an indoor option, use a broiler or oven grill, ensuring to baste frequently for authentic flavour.
- Rice: Short grain sushi rice is preferred, but medium grain rice can work if rinsed thoroughly before cooking.
Cooking Tips for Perfect Unagi
- Brush the sauce in thin layers to avoid burning from excess sugar.
- If using frozen eel, thaw slowly in the fridge overnight to maintain texture.
- Keep a steady medium heat when grilling for even caramelisation.
- Allow the eel to rest briefly before slicing to lock in moisture.
- Always use high-quality soy sauce and mirin for a balanced tare flavour.
How to Store and Reheat
Refrigeration Guidelines
Store leftover unagi in an airtight container within two hours of cooking. Properly sealed, it keeps for up to three days in the refrigerator. The sauce may separate slightly during storage, but this doesn’t affect quality when properly reheated.
Reheating for Best Results
Bringing unagi back to life requires gentle heat and moisture. Your oven provides the most reliable method. Preheat to 160°C and place the eel in a covered dish with a tablespoon of water or sake to create steam.
Heat for approximately 10 minutes until warmed through. This method helps maintain moisture whilst gently reviving the glaze. If you have extra tare sauce, brush some on before reheating to refresh the coating and add lustre.
Alternative Reheating Methods
A steamer works beautifully for leftover unagi. Place the eel on a heatproof plate and steam for about five minutes. This method closely mimics restaurant techniques and prevents the flesh from drying out or becoming rubbery.
Microwaving remains a last resort option. If you must use one, place the eel on a microwave safe plate, cover with a damp paper towel, and heat in 30 second intervals. Check frequently to avoid overcooking, which turns the delicate flesh unpleasantly tough.
Freezing Considerations
Unagi freezes reasonably well if wrapped tightly in cling film and then placed in a freezer bag. It keeps for up to one month frozen. Thaw overnight in the refrigerator before reheating using any method above for acceptable results.
Japanese Unagi (Grilled Eel)
Ingredients
- 4 fillets fresh unagi freshwater eel, cleaned and deboned
- 2 tbsp sake
- 2 tbsp mirin
- 2 tbsp soy sauce
- 1 tbsp sugar
- 1 tbsp water
- 1 tsp vegetable oil for grilling
- Steamed short-grain rice to serve
- Sansho pepper optional, for garnish
Instructions
- In a small saucepan, combine soy sauce, mirin, sake, sugar, and water. Place over medium heat and stir until the sugar dissolves completely. Allow the sauce to simmer gently for about 10 minutes until slightly thickened. Remove from the heat and set aside to cool.
- Preheat a charcoal grill or grill pan to medium heat. Lightly brush the grill with vegetable oil to prevent sticking. A traditional Japanese unagi grill imparts a delicate smokiness that defines the dish.
- Place the eel fillets in a bamboo steamer or over a heatproof plate and steam for 5–7 minutes. This step softens the flesh and reduces excess oil, ensuring a smooth, melt in the mouth texture before grilling.
- Lay the steamed eel skin side down on the grill. Cook for 5–6 minutes until the surface begins to brown lightly. Avoid moving the eel too much to prevent it from breaking apart.
- Brush the eel generously with the tare sauce, then flip carefully using tongs or a wide spatula. Brush the other side and continue grilling for another 3–4 minutes. The sugar in the sauce will begin to caramelise beautifully.
- Continue brushing and grilling the eel for another 5–7 minutes, turning occasionally. Each layer of glaze deepens the flavour and adds shine. The goal is a glossy, lacquered surface with lightly crisped edges.
- While the eel finishes cooking, portion freshly steamed rice into four bowls. Keep the rice warm and slightly firm, as it complements the rich sauce of the eel perfectly.
- Give the eel a final brush of sauce just before removing it from the grill. Allow it to rest for 2 minutes to let the juices settle and the glaze set evenly.
- Using a sharp knife, cut the eel fillets into neat portions. Traditionally, they are sliced diagonally for elegant presentation and easy eating.
- Lay the eel slices over bowls of rice and drizzle lightly with extra sauce. Sprinkle with a pinch of sansho pepper if desired. Serve immediately while hot, accompanied by pickles or miso soup for a complete meal.
