Preheat the oven to 400°F.
In a large bowl, stir together the
bell pepper, onion, beans, undrained tomatoes, and salsa.
Spray a 9-inch square pan with
vegetable oil spray. Spoon 1 cup bell pepper mixture into the pan. Arrange 4 tortillas
in the pan, overlapping as needed. Spoon half the remaining sauce over the tortillas.
Top with 1/2 cup cheese. Repeat.
Lightly spray a sheet of aluminum
foil with vegetable oil spray. Cover the pan with foil, lightly sprayed side down
prevent the cheese from sticking.
Bake for 30 minutes. Remove the
foil. Bake for 5 minutes more, or until hot and bubbly. Sprinkle with red pepper flakes
and cilantro. Cut into 4 squares.