In a bowl, whisk together the sesame oil, soy sauce, ginger, garlic, cilantro, peanuts, scallions, sugar, lime juice and chile oil; transfer half to a shallow dish. Add the steak and turn to coat. Cover and refrigerate overnight. Refrigerate the remaining marinade.
Light a grill. Add the stock to the reserved marinade. Bring the steak to room temperature, season with salt and pepper and grill over high heat until medium-rare, 5 minutes. Transfer the steak to a board and let rest for 5 minutes, then thinly slice across the grain. Serve the steak with the sauce.
Chef Jeff Starr pairs this juicy skirt steak with top Napa Valley Cabernets.