To begin, thoroughly rinse the pork bones under cold water to remove any impurities. Place the bones in a large pot and cover with water. Bring to a boil over high heat, and let boil for 10 minutes. Drain the water, and rinse the bones again to clean them well. This step is crucial to ensure a clean, flavourful broth.

In the same pot, return the cleaned pork bones and add enough water to cover them completely. Add the halved onion, garlic, ginger, and the white parts of the green onions. Bring the pot to a boil, then reduce to a simmer. Cover and cook for 6-8 hours, adding water as necessary to keep the bones submerged. The longer the simmer, the richer the broth.

While the broth is simmering, preheat your oven to 300°F (150°C). Season the pork belly or shoulder with salt and pepper. Sear the meat in a hot pan until browned, then transfer to an oven-safe dish. Bake for 2 hours, or until tender. Once done, allow the meat to cool slightly, then slice thinly for topping the ramen.

After simmering the broth, strain the liquid through a fine mesh sieve into a clean pot, discarding the bones and vegetables. Add soy sauce, sake, mirin, and miso paste (if using) to the broth. Stir and adjust seasoning to taste. The broth should have a deep, umami rich flavour.

In a small pot, boil the ramen noodles according to package instructions. Drain and set aside.

Prepare the soft-boiled eggs by placing them in boiling water for 6 minutes, then transferring them to an ice bath. Once cool, peel the eggs and slice in half.

To assemble the ramen, divide the noodles into four bowls. Pour the rich pork broth over the noodles. Top each bowl with slices of pork belly, soft-boiled egg halves, nori, bamboo shoots, green onions, and a sprinkle of sesame seeds.

For serving, drizzle a bit of chili oil over each bowl for an added kick. Present the ramen with extra toppings on the side, such as chili flakes or pickled ginger, to enhance the flavors. Enjoy your hearty, authentic Tonkotsu Ramen!