In a skillet on medium heat, add olive oil and onions.  Sauté the onions until soft (about 3 to 4 minutes).  Then add the canned roast beef and season with taco seasoning mix.  Continue to cook about 5 minutes, then remove from heat and cover to keep warm while preparing the taco shells.

In a separate skillet on medium heat, add about ½-inch vegetable oil.  Once the oil is hot, use a tong and dip half of a tortilla into the hot oil.  Then dip the other half of the tortilla into the hot oil, folding it into a taco shape, and continue to fry until desired crispness.  Place on a plate lined with paper towels.

Fill each fried taco shell with 2 to 3 spoonfuls of the beef taco meat, then top with taco sauce, shredded cheese, sour cream, lettuce, and tomatoes, or your favorite taco toppings and enjoy!