In a bowl, combine olive oil, lime juice, garlic, cumin, chili powder, paprika, salt, and pepper.
Coat steak with marinade and let rest for 15–30 minutes.
Preheat grill or grill pan to high heat.
Grill steak for 4–6 minutes per side, depending on thickness and desired doneness.
Remove steak and rest for 5 minutes before slicing against the grain.
Mix all avocado salsa ingredients in a bowl and gently toss.
Warm tortillas on the grill or in a skillet.
Assemble tacos with sliced steak and avocado salsa.