Heat oven to 425 degrees F. Place tortillas, overlapping slightly, on 2 baking sheets. Coat with cooking spray; flip over; coat bottoms. Bake 7 minutes; flip tortillas over; rotate pans. Bake until crisp and lightly browned, 7 minutes.
In large nonstick skillet, brown ground sirloin, breaking up clumps, 4 minutes. Stir in green pepper, red pepper and taco seasoning; cook 4 minutes.
Spread each tortilla with 2 tablespoons refried beans. Top each with heaping 1/4 cup meat and 2 tablespoons cheese. Bake 2 minutes to melt cheese. Serve fresh lime juice and sour cream on the side. Makes 12 pizzas.