1. Bring 1 cup of water to a boil in a small saucepan and drop in the spinach or watercress. As soon as it returns to the boil, drain the leaves in a sieve and run cold water over them. Set aside.
2. Arrange 2 pieces of fish and 2 cubes of tofu in each of 4 separate bowls. Sprinkle with ajishio and sake.
3. Steam the bowls of food for 6 minutes in an Oriental steamer or steamer substitute. Then add a sprig of blanched spinach or watercress to each bowl, and top each with 1 teaspoon of oboro kombu.
4. Serve with wedges of lemon, or chirizu dipping sauce, as a small, accompanying dish in a Japanese meal.