Prepare marinade (*see note below for non-marinated steak option) by whisking together all ingredients. Add marinade to a large ziploc bag and add steak. Make sure the steak is well coated in marinade and allow to rest for 6-24 hours.
Remove steak from marinade and shake off any excess moisture. Outdoor grill: Grill for 2-3 minutes per side for medium-rare. Indoor: place steak under a broiler for 6 minutes for medium-rare turning once during cooking. Alternatively, cook on a grill pan for 3 minutes and finish in a 425° oven for an additional 3 minutes
Lime Cilantro Slaw
In a large bowl whisk together mayonnaise, greek yogurt, lime juice, lime zest, garlic and jalapeno. Stir in cilantro, scallions, cabbage, salt and pepper. Can be made up to 1 day in advance.
Taco
Heat tortillas, either on the grill for 30 seconds or in a pan. Place a few slices of steak in a tortilla, top with a spoonful of slaw, and a slice of avocado and a sprinkle of cotija cheese. Squeeze fresh lime on top.
Notes
Dry Steak Method (no marinade)
Coat steak in 1/4 tsp kosher salt and 1/4 tsp ground black pepper. Follow grilling instructions