Preheat oven to 375 degrees F
Lightly grease two muffins tins with cooking spray. Cut 4 inch circles from the tortillas. You'll need about 16. Microwave the tortillas for about 10 seconds, until the tortillas are pliable. Place one tortilla into each muffin tin. Pressing the tortilla down on the bottom and around the sides. Bake for 10-12 minutes until the tortillas are lightly browned around the edges. Remove and set aside.
While the cups are baking, heat a large skillet to a medium-high heat and add oil. Add the onion and bell pepper. Cook until onions are translucent, about 5 minutes. Add ground beef. Crumble the meat as it cooks, about 5-8 minutes. Drain grease and add back to skillet. Sprinkle the taco seasoning over the cooked ground beef. Add water and bring to a low boil. Lower heat and cook 5-10 minutes, or until water is absorbed and meat is seasoned well.
Scoop a spoonful of meat mixture into each tortilla cup. Add about a tablespoon of beans and sprinkle with cheese. Add tomatoes, onions, lettuce, salsa and a dallop of sour cream.
Serve immediately and enjoy!