Begin by preparing the broth. In a large bowl, combine the beef broth, dongchimi brine, sugar, rice vinegar, and soy sauce. Mix thoroughly until the sugar dissolves. Taste and adjust the flavours with more vinegar for tanginess or sugar for sweetness, ensuring a balanced, slightly tangy sweet profile. Chill the mixture in the refrigerator for at least 2 hours, or until very cold.

While the broth chills, prepare the noodles. Boil a large pot of water, ensuring there's enough room for the noodles to cook without sticking. Add the naengmyeon noodles and cook according to package instructions (typically 3-4 minutes). Stir occasionally for even cooking.

Drain the noodles immediately after cooking and rinse under cold running water. This step is crucial to remove excess starch and cool the noodles. Use your hands to gently massage the noodles under the water for a bouncy texture. Drain thoroughly and set aside.

Prepare the toppings. Julienne the cucumber and thinly slice the Korean pear, keeping the slices crisp and fresh. Boil the egg, peel it, and cut it in half. Slice the brisket or cold beef thinly. Arrange all toppings on a plate for easy assembly later.

Check on the broth. Once thoroughly chilled, add a few ice cubes to enhance its coldness. This step ensures the dish stays refreshingly cold even as it’s served.

Portion the noodles into individual serving bowls, creating neat nests to enhance presentation. Pour the chilled broth over the noodles, ensuring they are fully submerged for the best experience.

Add the prepared toppings. Place the cucumber, pear slices, and beef neatly on top of the noodles. Add half a boiled egg to each bowl. Sprinkle with sesame seeds for added flavours, if desired.

Serve the naengmyeon immediately, alongside mustard paste, gochugaru, and extra vinegar or sugar for personal seasoning. For a traditional touch, pair with dongchimi radish slices or cold kimchi. To elevate the presentation, garnish with a few extra pear slices or a sprig of fresh mint. Encourage diners to mix the noodles thoroughly before eating to blend the flavours.