Sauté peppers and onions in olive oil for 5 minutes.
Add garlic and cook for 1 more minute. Remove from the pan and set aside.
Brown beef in the same pan. Then add tomato sauce, vinegar, Worcestershire sauce, thyme, Stevia and salt.
Stir peppers and onions back in with the beef and simmer for 10 minutes.
Serve on toasted buttered gluten-free rolls.