Cost per Serving:
1. Preheat oven to 300ºF. Wrap tortillas in foil and heat until warm and soft, about 10 minutes. Remove from oven and keep wrapped until ready to use.
2. While tortillas are heating, warm vegetable oil in a medium skillet over medium heat. Add onion and cook, stirring frequently, until softened, 3 to 5 minutes. Stir in black beans, corn and cherry tomatoes and cook until completely heated through, about 5 minutes. Stir in lime juice. Season with salt to taste.
3. Place a tortilla on counter. Spoon 1/4 of filling along center of tortilla. Sprinkle with 1/4 of cheese. Fold sides in over filling, then roll up tortilla to enclose. Repeat with remaining tortillas, filling and cheese. Cut burritos in half on diagonal. Serve immediately.