In a large non-reactive bowl or a gallon-sized zip-top bag, whisk together the olive oil, soy sauce, red wine vinegar, Worcestershire sauce, minced garlic, chopped rosemary, chopped thyme, orange zest, orange juice, black pepper, and red pepper flakes (if using).

Pat the skirt steak dry with paper towels. Place the steak into the prepared marinade, ensuring it is fully coated. Seal the bag or cover the dish and refrigerate for at least 2 hours, or preferably 4-6 hours, but no more than 8 hours (due to the acidity of the marinade).

Remove the steak from the refrigerator 30 minutes before cooking to allow it to come closer to room temperature, which promotes more even cooking. Season generously with salt just before cooking.

If grilling: Preheat your grill to high heat (450-500°F / 230-260°C). Lightly oil the grill grates. Remove the steak from the marinade, letting any excess drip off (do not wipe off, as the marinade provides flavor and helps with searing). Discard the remaining marinade.

If pan-searing: Heat a large cast-iron skillet over high heat until smoking lightly. Add 1 tablespoon of high-smoke point oil (like avocado or grapeseed) to the pan. Remove the steak from the marinade, letting any excess drip off. Discard the remaining marinade.

Place the skirt steak on the hot grill or in the hot skillet. Cook for 3-5 minutes per side for medium-rare (internal temperature 130-135°F / 54-57°C), or longer for desired doneness. Skirt steak cooks quickly due to its thinness, so watch it closely.

Transfer the cooked steak to a cutting board. Tent it loosely with foil and let it rest for 5-10 minutes. This crucial step allows the juices to redistribute, ensuring a more tender and flavorful steak.

Against the grain, slice the skirt steak into thin strips. Garnish with fresh chopped parsley. Serve immediately with your favorite sides like rice, beans, a fresh salad, or tortillas for tacos.