1. Heat oven to 375 degrees F.
2. Combine asparagus (if spears are thick, split in half lengthwise) and 2 tablespoons water in 9-inch glass pie plate. Cover and microwave on 100 percent power (High) 3 minutes until tender; drain.
3. Meanwhile, spread 2 teaspoons mustard on each of 4 slices of bread. Divide ham and arrange over bread.
4. Divide asparagus on ham; top each with 1 slice cheese. Transfer all slices of bread to cookie sheet. Bake 5 minutes until cheese melts and bread is warm.Make Tomato and Red Onion Salad::
5. Pour boiling water to cover over onion in small bowl; let stand 5 minutes. Drain well. Toss onion with tomatoes, olive oil, rice wine vinegar, parsley, salt and pepper in medium bowl.
6. Arrange ham-and-cheese slices on 4 serving plates. Top with remaining bread. Serve with Tomato and Red Onion Salad. Makes 4 servings.