Preheat oven to 350°. Heat oil in a large frying pan over high heat. Add chicken, mushrooms, onion, bell pepper, and seasonings and cook until chicken is browned and no longer pink inside, 6 minutes.
Spread 1/2 tsp. butter inside each roll and toast rolls, opened up, in oven on a baking sheet for about 4 minutes. Lay 1 lettuce leaf in each roll. Sprinkle cheese over lettuce, then divide chicken mixture among rolls. Serve with potato chips.
Note: Nutritional analysis is per serving.