Heat the olive oil in a large skillet over medium-high heat until shimmering.
Add the diced onion and bell peppers and cook, stirring, for 2–3 minutes until softened.
Add the minced garlic and cook for about 1 minute until fragrant.
Push the vegetables to the side, add the ground turkey to the pan, and cook, breaking it up with a spatula, until no longer pink and cooked through.
Reduce heat to low and stir in 3/4–1 cup tomato sauce, 3–4 tablespoons tomato paste, Worcestershire sauce, dried oregano (or Italian seasoning), red pepper flakes, salt, and cracked pepper until well combined.
If using rice, stir in 1–1½ cups cooked rice and add more tomato sauce if needed to reach desired sauciness; taste and adjust seasoning.
Serve hot topped with shredded cheese and chopped parsley if desired.