Preheat oven to 400 degrees F.
Heat a stove-top grill pan or griddle to medium-high heat and coat with cooking spray. Season shrimp all over with salt, black pepper and cumin. Place shrimp on the hot pan and cook 2 minutes per side, until bright pink and cooked through. Place pineapple on grill next to shrimp and cook 2 minutes per side, until golden brown. Remove shrimp and pineapple from grill and cut both into 1-inch chunks.
Arrange 4 tortillas on a flat surface. Top with, shrimp, pineapple, cheese, red peppers, and scallions. Place second tortilla on top. Transfer with hands or with a spatula, to a baking sheet. Place a second baking sheet on top to weigh down the tortillas. Bake for 10 minutes, or until cheese is melted and tortillas are golden brown.
While the quesadillas are baking, in a small bowl, using a spoon, combine sour cream, lime zest and garlic. Mix well to combine.
In a food processor, combine mango and lime juice. Puree until smooth and remove from food processor and place in a bowl. Using a rubber spatula, stir in cilantro.
Remove quesadillas from the oven. Cut quesadillas into wedges and serve with lime sour cream and pureed mango on the side.
Recipe courtesy of Robin Miller 2007