In a bowl, combine cilantro, oil, lime juice, garlic, oregano, brown sugar, cumin, orange juice, soy sauce, salt, and black pepper. Pour over the skirt steak, and marinate in the refrigerator for at least 2 hours or up to overnight.

Preheat your grill to high heat, about 600°F or hotter, for direct searing. Remove the steak from the marinade and grill for about 2 minutes per side until a deep crust forms and the internal temperature reaches 125–130°F for medium-rare.

Transfer the steak to a cutting board and let it rest for 10 minutes to lock in juices. Slice against the grain into thin strips, then cut into bite-sized pieces for easy taco building.

In a bowl, mash the avocados until slightly chunky, then fold in diced red onion, jalapeño, cilantro, lime juice, and salt. Mix until combined but still textured for a fresh, vibrant guacamole.

Blend Mexican crema, chipotles in adobo, and lime juice until smooth and creamy. Adjust the number of chipotles depending on your preferred spice level.

Warm the corn tortillas directly over the grill for 20–30 seconds per side until pliable. Fill each tortilla with shredded cheese, sliced steak, a spoonful of guacamole, and a drizzle of chipotle sour cream, then serve immediately.