Preheat the oil on medium-hi. (Choose the pan for frying the shells carefully. It should be just a little bigger than the taco shells in diameter, and have straight sides so the minimum amount of oil can be used. It's easier to handle the shells if the pan is fairly shallow - no more than 3 inches deep.).
In a separate pan, brown onion with meat and drain grease. Add tomato paste and spices.
Continue to simmer meat while frying shells. Fry each tortilla quickly, less than a minute each, folding in the middle while frying. Drain on paper towels. Add more oil if needed. Shells should still be fairly soft.
Fill taco shells with meat and serve. Cheese, lettuce, tomato, sour cream and taco sauce should be served with the tacos so that everyone can fix their own.