Marinate flank steak or skirt steak with lime juice, orange juice, garlic, cilantro, olive oil, cumin, chili powder, salt, and pepper
Refrigerate the steak for at least 1 hour or overnight
Preheat a grill or skillet over high heat
Cook the steak for 3 to 5 minutes per side, until charred and cooked to desired doneness
Rest the steak for 5 to 10 minutes
Chop the steak into small pieces
Warm corn tortillas on a skillet or directly over a flame
Fill each tortilla with chopped carne asada
Top with diced onion, chopped cilantro, and salsa
Add avocado, lime juice, or radishes if desired
Serve immediately