Cut the mizuna into 4 equal portions, and set aside.
Wipe clean the kombu slices with a damp, tightly wrung out kitchen towel. Cut several slices into the kombu with a pair of scissors, and place in your earthenware pot. Add enough water to cover the tofu.
Slice the tofu into bite-sized pieces (this time, I cut one block into 6 portions). After the kombu seaweed has softened, place the tofu in the water, add salt, then turn on the heat.
Taking care not to let the water boil, wait for the tofu pieces to warm up. When they start to waver in the water and have been heated through, add mizuna (or chrysanthemum greens). Once the vegetables are cooked through, you're done!
Garnish with your desired toppings. The standard choices in our household are ponzu, green onion, and yuzu pepper paste.
Story Behind this Recipe
This is a standard recipe for boiled tofu. I've added it here as a record for my family...
Be careful not to let the water boil while the tofu is cooking – you don't want to end up with porous, spongy tofu.