Preheat your grill or grill pan to medium-high heat.
Rub the flat iron steak with olive oil and season generously with salt and pepper.
In a small bowl, mix together the chili powder, ground cumin, and paprika.
Sprinkle the spice mixture over the steaks, rubbing it into the meat.
Grill the steaks for 4-5 minutes per side, or until they reach your desired level of doneness. Remove from the grill and let rest for a few minutes.
While the steaks are resting, heat a tablespoon of olive oil in a large skillet over medium heat.
Add the sliced bell peppers and onion to the skillet. Cook for 5-6 minutes, or until the vegetables are tender-crisp.
Add the minced garlic to the skillet and cook for an additional minute.
Thinly slice the flat iron steaks against the grain.
Return the sliced steak to the skillet with the vegetables. Squeeze the lime juice over the mixture and toss to combine.
Warm the flour tortillas on the grill or in a separate skillet for about 30 seconds on each side.
Serve the sliced steak and vegetable mixture in warm flour tortillas.
Garnish with your favorite toppings such as shredded cheese, sour cream, guacamole, salsa, and chopped cilantro.
Serve immediately and enjoy your Flat Iron Steak Fajitas!
4 servings