To start, mix all the marinade ingredients in a bowl until well combined. The mixture should be thick and aromatic, with its deep, reddish hue coming from the spices. Take your skirt steak and cut it into smaller 6-inch pieces for easier grilling. Place the steak in a ziplock bag or bowl with the marinade. Massage the mixture into the meat, ensuring every inch is coated.
Marinating is all about patience. Seal the bag or cover the bowl and refrigerate for at least an hour. Ideally, leave it overnight for maximum flavor absorption. During this time, the marinade will tenderize the steak, making it juicy and flavorful.
Heat your grill to 400°F for direct cooking. Place the marinated steak on the hot grates and cook for about 2 minutes per side, ensuring it gets a nice char. Use a meat thermometer to check that the internal temperature reaches 120-125°F for medium rare. Once off the grill, rest the steak for 10 minutes to lock in its juices.
While the steak rests, prepare the salsa. Char the tomatoes, tomatillos, jalapeño, and onion on the grill until they’re blackened. Add the charred veggies to a blender with garlic, lime juice, cilantro, chicken bouillon, and salt. Blend until you reach a slightly chunky texture. If needed, add a splash of water for a smoother consistency.
Warm your tortillas on the grill until they’re soft and pliable. Dice the rested steak into bite-sized cubes and layer it onto the tortillas. Top with salsa, diced onions, fresh cilantro, and a sprinkle of cotija cheese. Your tacos are now ready to serve!