In a bowl, combine the mayonnaise, cheese and salsa. Spread one-quarter of the mixture onto each of the 4 tortillas.
Sprinkle each tortilla with one-quarter of the corn, beans and onions. Fold the tortilla in half and press together.
Preheat a nonstick frying pan over medium heat. Place a tortilla on the pan and cook until lightly browned on the bottom. Flip and cook the other side until the cheese is melted and the tortilla is golden brown.
Remove from pan and repeat with remaining tortillas. To serve, cut into wedges.