Set oven control at broil and/or 550°.
Place top of steak 3 to 4 inches from heat.
Broil until medium, about 15 minutes per side; cool.
Cut steak into 3/8-inch strips.
Arrange in baking dish, 13 1/2 x 9 x 2 inches.
Layer mushrooms over meat; top with pepper rings.
Combine vinegar, oil and seasonings; pour over meat and vegetables.
Cover; refrigerate at least 3 hours, spooning marinade over vegetables occasionally.
With a slotted spoon, remove vegetables to lettuce cups.
Arrange strips of meat beside vegetables; garnish with tomatoes.