1. Preheat oven to 350 degrees.
2. Place crackers on cookie sheet; top with 1 slice each turkey, tomato and cheese.
3. Bake for 3 minutes or until cheese begins to melt; top with mustard.
4. Optional microwave version: Place 8 topped crackers on microwavable plate. Microwave on high 15 seconds or until cheese begins to melt. Repeat with remaining crackers.