- 3 dried pasilla chiles (see Note)
- 1/4 cup pitted prunes
- 2 tablespoons vegetable oil
- 1 small onion, finely diced
- 2 garlic cloves, minced
- 2 tablespoons sugar
- 1/4 teaspoon ground cinnamon
- 1 tablespoon sherry vinegar
- 1 tablespoon mezcal (see Note)
- 1/4 cup chicken stock
- Salt and freshly ground pepper
- One 1 3/4-pound flank steak
- In a shallow, heatproof bowl, cover the pasillas with 1 cup boiling water; carefully top with a small plate to keep the pasillas submerged. Let the chiles stand until softened, about 20 minutes. Meanwhile, in a small saucepan, cover the prunes with water and bring to a boil. Cover and let stand until softened, about 10 minutes.
- Drain the prunes and transfer to a blender. Transfer the pasillas to a work surface; reserve 1/2 cup of the soaking liquid. Discard the pasilla stems and seeds and coarsely chop the chiles. Add the pasillas and their reserved soaking liquid to the blender and puree.
- Light a grill or preheat a grill pan. In a medium saucepan, heat the vegetable oil. Add the onion and garlic and cook over moderately low heat until softened, about 7 minutes. Add the pasilla chile-prune puree along with the sugar, cinnamon and sherry vinegar and bring to a simmer over moderately high heat. Stir in the mezcal and stock and simmer for 1 minute. Season the adobo sauce with salt and pepper.
- Season the flank steak with salt and pepper and coat it with 1/4 cup of the adobo sauce. Grill the steak over moderately high heat, turning once, until medium-rare, about 5 minutes per side. Transfer the steak to a carving board and let rest for 5 minutes. Thinly slice the steak across the grain and serve with the remaining pasilla-prune adobo sauce.
The adobo sauce can be refrigerated in and airtight container for up to 2 days. Bring to room temperature before serving.
Pasilla chiles (also called chiles negros) are long, black, dried chiles. They are available at Latin markets or from gourmetsleuth.com. Mezcal, a Mexican spirit, is available at many liquor stores.
Southern Italian red wines often have a plummy note, which goes well with meat served with fruit-inflected sauces. Look to Puglia or Sicily.