Combine the soy sauce, olive oil, vinegar, Worcestershire sauce, honey, mustard, garlic, and hot sauce in a mixing bowl. Add the cayenne, paprika, red pepper flakes, oregano, cumin, and a pinch of salt and pepper. Mix everything together until smooth. This is where the magic begins!
Place the flank steak in a resealable plastic bag or shallow baking dish. Pour the marinade over the steak, ensuring it’s completely covered. Massage the marinade into the meat to help the flavors penetrate. Seal the bag or cover the dish and refrigerate for at least 1 hour, but overnight is best for deeper flavor.
When you’re ready to cook, preheat your grill or grill pan to medium-high heat. Lightly oil the grill grates to prevent sticking.
Remove the steak from the marinade, letting the excess drip off, and place it on the grill. Discard the marinade. Grill for about 3-4 minutes per side for medium-rare, or adjust cooking time based on your preferred doneness. Use a meat thermometer for precision (125°F for rare, 135°F for medium-rare).
Transfer the steak to a cutting board and cover it loosely with aluminum foil. Allow it to rest for 10 minutes; this locks in all those delicious juices. When slicing, cut against the grain into thin strips for maximum tenderness.