Prepare the vegetables by coring the green peppers and slicing them into thin strips. Thinly slice the onions and arrange them on a cutting board.

In a large mixing bowl, combine the cooked shredded beef with the prepared peppers and onions. Drizzle in lime juice and oil, adding chopped garlic along with salt and pepper. Toss together thoroughly.

Cover the bowl with plastic wrap and marinate in the cooler for at least 15 minutes, up to 1.5 hours to infuse deeper flavor.

Preheat a large skillet over medium-high heat until hot enough that a drop of water sizzles.

Add the marinated beef and vegetable mixture to the hot skillet, frying for about 3 to 5 minutes until crispy. Turn occasionally to ensure even cooking.

Remove from heat and serve in gluten-free tortillas or lettuce wraps, adding desired toppings.