Whisk together the Worcestershire sauce, tamari, vinegar, hot pepper sauce, chili powder, cumin, and salt. Pour in a zip bag with the meat; zip shut and refrigerate for 4 to 8 hours or overnight.
Heat a large skillet over medium-high heat. Melt 2 teaspoons butter and saute the pepper strips and onion, stirring often, until water has evaporated the peppers and onions are tender.
Add the garlic and sauté for an additional minute or so. Transfer veggies into a bowl and set aside.
Add the meat and its marinade to the pan. Cook until meat is the desired doneness (well for chicken).
Sprinkle the xanthan gum and stir it into the meat; if there isn't any liquid left, add a tablespoon or two of water. Heat for another 2 or so minutes until slightly thickened.
Return the veggies to the pan and mix everything together.
Serve on low carb tortillas or alone in a bowl and garnish with fresh chopped cilantro.
This resulting dish (when made with chicken breast) is Neutralific (THM FP). Enjoy only one low carb tortilla or no tortillas for a fajita bowl.For a Carbalicious (THM E) twist, add about 1/4 to 1/2 cup cooked brown rice to your fajita.For a Fatastic (THM S) twist, add guacamole, cheese, and sour cream. You can also use a fattier steak like beef.Nutrition facts based on using chicken breast.