Step 1

Prepare the following, adding each to the same medium bowl as it is complete: Cut the core from 1/2 medium green cabbage; cut the leaves into 1-inch pieces until you have about 3 cups. Dice 2 medium yellow onions (about 3 cups) Finely chop 4 medium scallions (about 2/3 cup).

Step 2

Heat 1/4 cup vegetable oil in a large heavy-bottomed pot or wok over medium heat until shimmering. Add the cabbage mixture and cook until the onions look translucent and the cabbage starts to brown in spots, 4 to 6 minutes. Meanwhile, cut 8 ounces pork belly or pork loin into 1-inch pieces. Peel and mince 1 (1-inch) piece ginger (about 1 tablespoon).

Step 3

Add the pork and ginger and cook until the pork is no longer pink, 3 to 5 minutes. Make a well in the center by pushing everything to the sides. Add 1/4 cup Korean black bean paste to the well and use a spatula to stir-fry the paste in the pool of oil. Mix into the vegetables and cook until glossy and the vegetables are well coated, 3 to 5 minutes.

Step 4

Add 1 tablespoon plus 1 1/2 teaspoons granulated sugar, 1 tablespoon oyster sauce, 1 tablespoon soy sauce, and 1 1/2 teaspoons chicken bouillon powder. Stir-fry until everything is well incorporated, 1 to 2 minutes.

Step 5

Add 1 1/2 cups of the water and stir to combine. Simmer, stirring occasionally, until the liquid is slightly thickened, 8 to 10 minutes. Meanwhile, place the remaining 1/4 cup water and 2 tablespoons potato starch or cornstarch in a small bowl and stir until the starch is dissolved. Bring a large pot of water to a boil over medium-high heat. Cut 1 medium Persian cucumber into matchsticks.

Step 6

While stirring constantly, add the starch mixture and simmer until the liquid thickens to the consistency of a thick gravy, 2 to 3 minutes. Add 1 teaspoon apple cider vinegar and stir to combine. Remove the pot from the heat.

Step 7

Add 7 ounces fresh jjajangmyeon noodles (or 2 ounces dried) to the boiling water and cook according to the package instructions. Drain, rinse, and transfer the noodles to 2 to 3 individual serving bowls. Top with the sauce and garnish with the cucumber. Toss before serving.