In a large skillet, cook pepper and onion in vegetable oil over medium-high heat for 3-5 minutes. Remove from heat

Lightly coat one side of tortilla with cooking spray

On the uncoated side of 2 tortillas, divide cheese. Top with onion mixture and cilantro. Top with tortilla, coated side up

Heat large skillet over medium. Cook quesadillas 4-5 minutes, until brown

Slice and serve with sour cream