1. Preheat oven to 250ºF. In a bowl, mix mango, bell pepper, scallions, lime juice and red pepper flakes.
2. Arrange turkey on top of 4 tortillas. Top with mango mixture and shredded cheese, then top with remaining 4 tortillas.
3. Warm a large, nonstick skillet over medium heat. Cook quesadillas 1 at a time, turning once, until golden brown on both sides, about 8 minutes total. Transfer to a large plate and keep warm in oven while cooking remaining quesadillas (you can stack them all on one plate). When all the quesadillas have been cooked, cut each into wedges and serve hot.