Spray tortillas on both sides with a butter-flavored spray and sprinkle lightly with salt. Place directly on the rack and bake for 10 minutes at 350°. Remove and set aside.
Drain the pinto beans and discard liquid. Coat a medium skillet generously with a vegetable spray and cook the onion over medium heat, stirring constantly, until lightly browned. Put the onion in a food processor fitted with the metal blade and add the beans, chili powder, cheese, and picante sauce. Process to purée, then return to the same skillet, over medium heat. Add garlic salt, salt, and pepper to taste and heat until bubbling and hot. Set aside.
In a separate skillet, use a vegetable coating spray and sauté the red onion over medium heat, using vegetable spray, until browned, and set aside.
To assemble the chalupas, spread about 2 tablespoons of the beans on each tortilla. Top with combined lettuces, red onion, cheese, tomatoes, and radishes. Serve 2 or 3 per person.
Advance Preparation: You may prepare the beans a day in advance.