Chile-Marinated Skirt Steak (Carne Asada en Adobo de Guajillo)

Remove stems, seeds and membranes from chiles. Heat a heavy skillet over medium-high heat. Add chiles and toast, using tongs to turn and press down on them frequently, until very fragrant, 2 to 3 minutes. Transfer to a bowl and add enough cold water to cover. Place a plate on top to keep them submerged and soak until very soft, about 30 minutes. Drain. Transfer the chiles to a blender and add 1/2 cup fresh water, garlic, 1/2 teaspoon salt, vinegar, sugar and cumin. Blend until very smooth, gradually adding a little more water, if necessary, to make a smooth sauce.

Place steak in a large shallow glass dish and season with the remaining 1 teaspoon salt. Add the marinade and turn to coat well. Cover and marinate in the refrigerator for at least 2 hours and up to 1 day.

To grill: Preheat grill to medium-high.

Lightly oil the grill rack (see Tip). Grill the steak, turning once, 6 to 7 minutes total for medium-rare skirt steak or 9 to 12 minutes for medium-rare flank steak. Transfer to a clean cutting board and let rest for 5 minutes before thinly slicing.