Clean the crabs thoroughly.
Cut the radish, onion, zucchini, and tofu into bite-sized pieces.
Put water and kelp in a pot to make broth.
Dissolve soybean paste and red pepper paste into the broth.
Add radish, onion, and zucchini, and bring to a boil.
Add the crabs, tofu, spicy chili pepper, and garlic.
Simmer until all ingredients are fully cooked.