How to Make It
In a heatproof bowl, cover the anchos with boiling water and let stand for 15 minutes. Drain the chiles, discarding any seeds and stems, and coarsely chop. In a food processor, pulse the chiles and garlic until finely chopped. Add the pumpkin seeds, almond butter, vinegar and 1/2 cup of warm water; pulse to a coarse paste. With the machine on, add the 1/2 cup of oil in a steady stream. Season with salt and pepper. Scrape the almond sauce into a bowl; don't worry if the oil separates.
Preheat a grill pan and oil the pan. Season the steak with salt and pepper and grill over high heat for about 6 minutes, turning once, until lightly charred. Let the steak rest, then thinly slice across the grain and serve with the almond sauce.