Slice 1 to 1.5 pounds of flank steak or skirt steak against the grain
Mix lime juice, olive oil, minced garlic, chili powder, cumin, paprika, salt, and black pepper
Marinate the steak for 30 minutes to 4 hours
Slice bell peppers and onions into thin strips
Heat a large skillet or grill pan over medium-high heat
Cook the steak for 2 to 4 minutes per side until browned and cooked to desired doneness
Transfer the steak to a plate and let it rest for 5 minutes
Cook the peppers and onions in the same pan until tender-crisp
Slice the steak into thin strips
Return the steak to the pan and toss with the vegetables
Serve with warm tortillas and toppings like salsa, guacamole, sour cream, and cheese