Preheat oven to 400 degrees. Cut off the tops of 4 bell peppers about 1-inch down from top. Clean out seeds and membranes. Throw away the tops. Set peppers aside.
In a small microwave-safe bowl or plate, add onions, chopped red bell peppers, and cook in microwave for 2 minutes, to soften.
In a large nonstick pan, heat 2 teaspoons olive oil. Add ground turkey, softened onions/bell peppers, and garlic. Cook turkey until no longer pink, stirring often. Be sure to break up ground turkey into a crumble as it cooks.
Stir in tomato sauce, ketchup, barbecue sauce, mustard, Worcestershire sauce. Season with a little black pepper and red pepper flakes. Mix well. Continue to cook about 5 minutes until heated through. Remove from heat.
Stuff each bell pepper with ground turkey mixture. Place each in a 9-inch baking dish. Pour 1 cup water in bottom of baking dish. Cover dish with foil and bake for 45-50 minutes until bell peppers are soft. If peppers are not soft enough, cook about 5 more minutes.
Once cooked, cooled and wrapped, they freeze great!