Wash and trim the vegetables. Shred the cabbage and cut the carrots into fine julienne strips. Cut the green beans diagonally into thin strips. Parboil the cabbage for a few seconds in a large pot of lightly salted, rapidly boiling water; remove from the water, rinse immediately in cold water, drain, and pat dry. Parboil the carrots and the green beans separately in the same way, then rinse and pat dry.
Lightly toast the sesame seeds for the dressing and grind to a paste, or use ready-made sesame paste. Cream in the tofu and mirin and season to taste with a little salt.
Just before serving, fold the vegetables into the dressing. Serve small mounds of the salad in deep pottery bowls of a contrasting color and sprinkle with a few sesame seeds to garnish.