Heat gas or charcoal grill. Lightly spray one side of each tortilla with cooking spray. On unsprayed side of each of 4 tortillas, spread 1/4 cup beans. Sprinkle each evenly with 1/4 of the bell pepper, tomato, green chiles and cheese. Top each with remaining tortilla, sprayed side up; press down firmly.
Place quesadillas on grill. Cover grill; cook over medium heat 6 to 8 minutes, turning once, until cheese is melted.
To serve, cut each quesadilla into quarters. Serve with sour cream.