3 whole dried ancho chilies, stems and seeds removed (see note above)
3 whole dried guajillo chilies, stems and seeds removed (see note above)
2 whole chipotle peppers, canned in adobo
3/4 cup fresh juice from 2 to 3 oranges, preferably sour oranges
2 tablespoons fresh juice from 2 to 3 limes
2 tablespoons extra-virgin olive oil
2 tablespoons soy sauce
2 tablespoons Asian fish sauce
6 medium cloves garlic
1 small bunch cilantro, leaves and tender stems only, divided
1 tablespoon whole cumin seed, toasted and ground
1 teaspoon whole coriander seed, toasted and ground
2 tablespoons dark brown sugar
Kosher salt
2 pounds skirt steak (2 to 3 whole skirt steaks), trimmed and cut with the grain into 5- to 6-inch lengths
Warm corn or flour tortillas, lime wedges, diced onion, fresh cilantro, and avocado, for serving