In a large ziploc bag, whisk together the olive oil, soy sauce, lime juice, cilantro, orange juice, vinegar, sugar, pepper, cumin, onion, garlic, and jalapeño pepper.
Add the skirt steak to the bag and marinate overnight or for at least 8 hours.
When ready to grill, liberally season the steak with salt and pepper.
Grill the steak covered until it is golden brown, perfectly charred, and tender (cooked to medium rare, or 145°F).
To check for doneness, insert an instant-read thermometer horizontally into the side of the steak, being careful not to touch bone, fat, or the grill.
Allow the steak to rest before slicing on a cutting board.
Serve with tortillas and garnishes of your choice and enjoy!