1.Combine 8 cloves minced garlic, 1 tsp ginger, 0.25 cup soy sauce, 1 tbsp gochugaru, and 0.25 tsp ground black pepper in a bowl. Mix well and set aside.
2.Arrange the 8 ounces Korean radish in the bottom of a large heavy skillet. Arrange the 1 medium onion slices over the radish.
3.Place the pieces of fish on top, side by side.
4.Spoon the seasoning mixture over top of the fish. Add 2 cups water along the edges of the skillet so that the seasoning mixture remains on top of the fish.
5.Cover and cook over medium high heat for .
6.Open the skillet and add the 1 green chili peppers and 1 green onion. Spoon some of the broth over top a couple of times. Cover and reduce the heat to medium. Cook for another .
7.Uncover and spoon some of the broth over the top of the fish to season it evenly. Be sure not to move or turn over the fish because it's so soft that it will break easily.
8.Reduce the heat to low and simmer for to cook the radish thoroughly.