Spray 10-inch skillet with cooking spray; heat over medium heat. Cook onion and garlic in skillet about 5 minutes, stirring occasionally, until onion is tender but not brown. Stir in beans and chilies; cook until hot.
Place one-fourth of the bean mixture on center of each tortilla. Top with cheese and tomato.
Fold one end of tortilla up about 1 inch over filling; fold right and left sides over folded end, overlapping. Fold remaining end down. Place seam side down on serving platter or plate.