Serves 6 to 8 as a taco filling
- Combine steak and 5 ounces hot sauce in a large plastic food bag. Close the bag and work the hot sauce into the meat, turning meat in the bag. Marinate in the refrigerator at least 1 hour and up to 24 hours, turn occasionally.
- Preheat a gas grill to medium-high heat or prepare a charcoal grill.
- Brush onion slices with olive oil and sprinkle with salt and black pepper. Grill the onions, carefully turning them once, until golden and tender, about 10 minutes. Cool, then separate into rings.
- Remove the steak from the marinade, brush with olive oil and season with salt and black pepper. Grill the steak, turning only once, until medium-rare, about 10 minutes total. Remove to a cutting board and slice thinly against the grain.
- Mix the sliced steak with the grilled onions on a heated platter. Serve with extra hot sauce or salsa, chopped cilantro and warm tortillas.