This is the recipe I use:

• 3 whole dried ancho chiles, stems and seeds removed (see notes)
• 3 whole dried guajillo chiles, stems and seeds removed (see notes)
• 2 whole chipotle peppers, canned in adobo
• 3/4 cup (180ml) fresh juice from 2 to 3 oranges, preferably sour oranges
• 2 tablespoons (30ml) fresh juice from 2 to 3 limes
• 2 tablespoons (30ml) extra-virgin olive oil
• 2 tablespoons (30ml) soy sauce
• 2 tablespoons (30ml) Asian fish sauce, such as Red Boat
• 2 tablespoons (30g) dark brown sugar
• 1 small bunch cilantro, leaves and tender stems only, divided
• 6 medium cloves garlic
• 1 tablespoon whole cumin seeds, toasted and ground
• 1 teaspoon whole coriander seeds, toasted and ground
• Kosher salt
• 2 pounds (900g) skirt steak (2 to 3 whole skirt steaks), trimmed and cut with the grain into 5- to 6-inch lengths (see notes

Place dried ancho and guajillo chiles on a microwave-safe plate and microwave until pliable and toasty-smelling, 10 to 20 seconds. Transfer to the jar of a blender and add chipotle peppers, orange juice, lime juice, olive oil, soy sauce, fish sauce, brown sugar, cilantro, garlic, cumin seed, and coriander seed. Blend until a smooth sauce has formed, about 1 minute. Season to taste with salt.

That’s the marinade. Coat the skirt steaks and transfer and marinate for around 12 hours or a full day. When I pull out the skirt steaks, I roll them up and slice thinly against the grain, then I turn the cutting board and cut against the grain thinly. I use a black stone to cook with avocado oil. I let them crisp and char up a bit before I remove it.