Heat 1tsp oil in a small saucepan, add the refried beans along with ground cumin, salt and pepper. Cook till heated through. Add water if the beans look too thick.
Heat 2tbsp oil in a sauté pan, add the chopped onions and peppers. Cook till the veggies are crisp tender, about 6~8 minutes.
To assemble: Spray a nonstick tawa/ griddle with cooking spray, place the tortilla and cook till heated through and slightly charred. Remove on to a plate.
Spread 2~3tbsp of beans mixture and top it with the veggies, shredded cheese and sour cream. Serve immediately.