Pour vegetable oil, lime juice, soy sauce, garlic, chili powder, cumin and oregano into a large bowl. Whisk to combine. Place steak pieces into the marinade; toss to coat all the steak pieces. Cover with a lid and place in refrigerator. Allow steak to marinate for 2 hours or up to 12 hours.
Heat a large skillet over medium-high heat. Using a slotted spoon, remove half of the steak from the marinade. (*Cook steak in two separate batches to prevent over-crowding the skillet.) Place steak pieces in hot skillet. Cook and stir for about 4 minutes or until steak reaches your desired temperature.
Place cooked steak onto a plate and tent with foil to keep warm. Cook remaining batch of steak to your desired temperature. Discard marinade.
Serve warm steak in warmed tortillas topped with desired amount of fresh cilantro, red onion and lime juice. Enjoy!