Rinse the fish quickly under cold running water and cut into small pieces. Wash and cut the vegetables. Bring the water and kombu to a boil in a saucepan, add the fish and salt, cover, and simmer over low heat for 25 minutes. Add the vegetables, return to a boil, and simmer over low heat for 5 minutes. Season with tamari and grated ginger and simmer for 2 minutes. Stir with a wooden spoon to mix the vegetables and fish evenly. Garnish with chopped parsley. Serves 6.