1tablespoonsoup soy sauce (or you can just use salt to taste)
Salt and pepper
Clean the oysters by gently swishing around in salted water. Drain. Rinse again in clean water and drain again.
Cut the radish into thin, bite size pieces (about 1-inch square, 1/4-inch thick). Thinly slice the scallions crosswise and slightly diagonally.
Add 6 cups of water, the radish and optional dried kelp to a medium size pot. Bring it to a boil over high heat. Reduce the heat to medium high, and cook until the radish is softened, about 5 minutes.
Remove the kelp if used, and drop the oysters in. Add the garlic, and season with salt (about 1 teaspoon) and pepper to taste. Cook for another minute after the soup comes to a boil again. Do not overcook oysters. Remove the scum. Drop the scallions in right before turning off the heat.