Prepare the Steak: Slice flank or sirloin steak against the grain into thin strips, about 1/4 inch thick.

Marinate the Steak: In a bowl, combine olive oil, lime juice, minced garlic, salt, black pepper, and fajita seasoning mix. Add steak strips and toss to coat. Let marinate for 15-20 minutes.

Cook the Steak: Heat cast iron skillet over medium-high heat, add olive oil, then place marinated steak strips in a single layer. Cook for 2-3 minutes per side until browned.

Sauté the Vegetables: In the same skillet, add sliced bell peppers and red onions. Sauté for 5-7 minutes until softened, seasoning lightly with salt and fajita seasoning.

Prepare the Base: Heat cauliflower rice in a separate pan for 3-5 minutes until tender, or prepare shredded lettuce as a base.

Assemble the Bowl: Start with cauliflower rice or shredded lettuce as the base, layer with sautéed veggies, and top with steak.

Add Garnishes: Finish with avocado or guacamole and cilantro. Squeeze fresh lime juice over the dish before serving.