Heat oil in a large saucepan over medium heat. Stir in beans and corn, then add the salsa; mix well. Cook until heated through, about 3 minutes.

Melt some of the butter in a large skillet over medium heat. Place a tortilla in the skillet, sprinkle evenly with cheese, then top with some of the bean mixture. Place another tortilla on top, cook until golden, then flip and cook on the other side. Melt more butter as needed, and repeat with remaining tortillas and filling.

Note: For leftovers, store the bean mixture in the fridge in an airtight container. When ready to eat, reheat bean mixture in microwave and start at Step 2.