This is my own creation adapted form my meat-eating days.
Open sandwich rolls and coat one inside part with mayonnaise if desired. Place 2 slices of cheese inside each roll. Heat briefly in microwave or oven to melt cheese.
Meanwhile, in a skillet add enough olive oil to sauté veggies (1-2 tbsp). Heat a bit and then add veggies to pan tossing in oil to coat. Stir and cook to desired doneness. Salt and pepper to taste. The veggies should be tender but still a bit crisp. Turn off burner and fill rolls with vegetable mixture. Enjoy!
Note: If you like your food on the spicy side, you can chop up a jalapeno pepper and add it to the vegetable mixture toward the end of the cooking time. You can also add a little hot sauce for a similar spicy taste.
If you chop all your veggies in advance this only takes minutes to prepare.