In a large pot, combine the beef brisket with approximately 8 cups of water. Bring to a rolling boil, then reduce to a gentle simmer for about 30 minutes.

Carefully skim any foam or impurities that have risen to the surface of the broth using a slotted spoon.

Stir in 1/4 cup of soy sauce, 2 tablespoons of gochujang, 1 tablespoon of gochugaru, and the minced garlic. Mix thoroughly.

Add the chopped onions, sliced napa cabbage, cubed tofu, and sliced daikon radish, then simmer for an additional 20 minutes.

Heat 1 tablespoon of sesame oil in a skillet over medium heat. Sauté the sliced green onions until fragrant, about 2-3 minutes.

Add the sautéed green onions into the soup, taste, and adjust seasoning with salt and pepper.

Ladle the soup into bowls and serve hot with cooked white rice on the side.