In a small bowl, whisk together ketchup, vinegar, sweetener, mustard, and worcestershire sauce to create the sauce. Add a dash of cayenne pepper, if you like it spicy. Set aside.
In a skillet prepared with cooking spray, add your onion and bell peppers. Cook until tender, about 4 minutes.
Meanwhile, place your turkey burger alone on a microwave safe plate and cook for 60 seconds in the microwave.
Remove your burger from the microwave and place it in a food processor to pulse.
Add the burger to the pan and cook for 1 minute. Add sauce to the pan, and stir to combine cooking for an additional minute. Salt and pepper, if desired.
Place your bun in the microwave wrapped in a paper towel for 15 seconds to finish the defrosting process. Toast, if desired.
Place your bun on a plate, and add the meat and veggie mixture. Load the bun high to allow for the entire mixture to sit on the bun. Serve with roasted sugar snack peas for a fresh and free addition and to get your veggies in!