Whisk together the avocado oil, lime juice, chili powder, smoked paprika, garlic powder, cumin, onion powder, salt, and black pepper.
2 tbsp avocado oil, 2 tbsp lime juice, 2 tsp chili powder, 1 tsp smoked paprika, 1 tsp garlic powder, 1 tsp cumin, 1/2 tsp onion powder, 1 tsp salt, 1/2 tsp black pepper
Place the steak in a shallow dish or resealable bag, pour the marinade over it, and turn to coat. Refrigerate for at least 30 minutes or up to eight hours.
1 1/2 lbs flank steak or skirt steak
While the steak marinates, make the optional sauce by whisking together the yogurt, lime juice, garlic powder, and salt. Add water 1 tablespoon at a time until it reaches a drizzleable consistency, then refrigerate until needed.
1/2 cup plain dairy-free yogurt or Greek-style yogurt, 1 tbsp lime juice, 1/2 tsp garlic powder, 1/4 tsp salt
Heat the grill to medium-high, approximately 450°F to 500°F. Clean the grates.
Remove the steak from the marinade and let the excess marinade drip from the steak before placing it on the grill over direct heat. Discard the used marinade.
Cook for approximately 4 to 6 minutes per side for flank steak, depending on its thickness. (cook to 125°F to 130°F for medium rare)
Transfer the steak to a clean cutting board and let it rest for 10 minutes. Identify the direction of the grain, then slice the steak thinly across it.
Warm the tortillas briefly on the grill, then fill them with cabbage, sliced steak, avocado, mango salsa, cilantro, and creamy lime sauce if using. Serve with lime wedges.