1. In glass baking dish, combine salt, mustard and pepper. Stir in the vinegar, oil, lemon juice, scallions and parsley. Mix thoroughly. Add steamed asparagus and tomato wedges. Cover and refrigerate for several hours or overnight.
2. Just before serving, peel bananas and cut into diagonal slices. Arrange asparagus, tomatoes and bananas on lettuce leaves on serving platter.