Make the beef broth: In a large pot combine Water and Beef Brisket with a halved Onion, a few smashed Garlic cloves, sliced Ginger, a tied bunch of Scallions and a teaspoon of Black Peppercorns. Bring to a boil, skim any foam, then reduce to a gentle simmer and cook until the brisket is tender, about 1.5–2 hours.
Remove the meat and set aside; reserve the cooking liquid. When the brisket has cooled enough to handle, slice it thinly and keep it as your sliced Cooked Beef Brisket. Strain the broth through a fine sieve, discard solids, and cool the liquid to room temperature.
While the broth cools, prepare the garnishes: soft-to-medium boil the Eggs for about 7–8 minutes (or 9–10 minutes for fully hard-cooked yolks), then plunge into ice water, peel and halve. Julienne the Korean Pear and cut the Cucumber into thin matchsticks. Thinly slice the Dongchimi Radish. Reserve some thinly sliced Scallions for garnish.
Finish and chill the broth: Once the strained broth is cool, stir in several ladles of Dongchimi Brine and taste. Season gradually with Fine Sea Salt, a pinch of Sugar and a splash of Mild Grain Vinegar until you reach a balanced sweet-sour-salty profile. Refrigerate until very cold, then add several Ice Cubes just before serving to make it icy.
Cook the noodles: Bring a pot of water to a rolling boil and cook the Dried Naengmyeon Noodles according to package directions (usually 3–4 minutes) until just al dente. Drain and rinse immediately under very cold running water, then drain well and toss briefly to prevent clumping.
Assemble bowls: Divide the chilled noodles between bowls, ladle the icy broth over them, and arrange toppings—halved Eggs, julienned Korean Pear, Cucumber matchsticks, Dongchimi Radish slices and thin slices of Cooked Beef Brisket. Scatter remaining Scallions and a light crack of ground Black Peppercorns if desired.
Serve with condiments: Offer a small spoonful of Korean Mustard on the side and extra Dongchimi Brine or Mild Grain Vinegar for guests to adjust acidity. Enjoy immediately while the broth is icy and the noodles are chewy.
