Preheat oven to 400 F. Place tortillas on an ungreased baking sheet, lightly spray with cooking spray and prick all over with a fork. Bake for 5-6 minutes, until they are puffed and begin to turn golden. Remove from oven and allow to cool. Keep the oven on.
In a large skillet, heat the olive oil over medium heat. Add the sliced onions to the skillet, season with salt and pepper to taste, and cook over medium-low heat, stirring occasionally, until onions turn translucent and begin to caramelize (about 8-10 minutes). When the onions are almost done, add the diced peppers and cook just until they begin to soften. Remove skillet from heat.
Spoon about 1-2 tablespoons of enchilada sauce over each of the baked tortillas. Top with the onions and veggie mixture, olives and cheese. Place it back in the oven and cook for 5-6 more minutes, until the cheese has melted. Remove from oven and garnish with fresh cilantro and sour cream.