Whisk the olive oil, soy sauce, lime juice, cilantro, orange juice, vinegar, sugar, pepper, cumin, onion, garlic and seeded chile pepper in a large ziploc bag until well combined.
Add skirt steak to ziploc bag with marinade and allow to marinade overnight preferably or at least 8 hours.
When ready to grill, liberally season with salt and pepper.
Grill covered until golden brown (cooked to medium rare (145°F) doneness), perfectly charred and tender
To determine doneness, insert an instant-read thermometer horizontally into the side of the steak. Place the thermometer in the thickest part of the steak and do not let it touch bone, fat or the grill.
Allow to rest before slicing on a cutting board.
Serve with salsas, tortillas and garnishes of your choice and enjoy!