Begin by marinating the steak in olive oil, lime juice, chili powder, cumin, salt, and pepper for at least 30 minutes.
Preheat a grill or skillet over medium-high heat.
Remove the steak from the marinade and cook for about 5-7 minutes on each side until desired doneness.
Transfer the steak to a cutting board and let it rest for a few minutes before slicing.
While the steak rests, add sliced bell peppers and onion to the grill or skillet.
Sauté the vegetables for about 5 minutes until tender.
Slice the steak against the grain into thin strips.
Warm the tortillas in a separate pan or microwave.
Assemble the fajitas by placing steak and vegetables on the tortillas, adding cilantro and lime juice to taste.
Serve immediately and enjoy!