Heat olive oil in a large skillet over medium heat. Add diced onion and bell pepper, and cook until softened, about 5 minutes.

Add minced garlic and cook for an additional minute until fragrant.

Increase heat to medium-high and add ground turkey to the skillet. Season with salt and pepper. Cook, breaking up the meat with a spoon, until the turkey is browned and cooked through, about 5 to 7 minutes.

Stir in tomato sauce, tomato paste, brown sugar, Worcestershire sauce, apple cider vinegar, and mustard. Reduce heat to low and simmer the mixture until thickened, about 10 minutes, stirring occasionally.

Serve the turkey mixture on toasted whole wheat hamburger buns.