Whisk together olive oil, soy sauce, lime juice, garlic, cumin, smoked paprika, brown sugar, salt, and pepper in a bowl. Place the skirt steak in a resealable bag and pour the marinade over it. Seal the bag, ensuring the steak is fully coated, and refrigerate for at least 2 hours (overnight is even better!).

Load fresh parsley, cilantro, garlic, red wine vinegar, and red pepper flakes into a food processor. Pulse until finely chopped. With the motor running, slowly drizzle in olive oil until emulsified. Season with salt and black pepper to taste.

Preheat your grill (or grill pan) on high heat. Remove the steak from the marinade and pat it dry with paper towels. The dryness helps achieve a great char.

Grill the steak for about 3-4 minutes per side for medium-rare, or adjust the time based on your preferred doneness. While grilling, brush some chimichurri on the meat to enhance the flavor. Once cooked, transfer the steak to a cutting board and allow it to rest for 5 minutes.

Slice the steak against the grain into thin strips for maximum tenderness. Drizzle generously with chimichurri and serve the remaining sauce on the side.