Heat a large skillet over medium-high heat. Add ground beef, 1/4 onion, chopped and garlic, stirring until browned. Add chili powder, cumin and salt, tossing to mix. Add 1/4 cup water, reduce heat to low and let simmer until almost dry; remove from heat. Add about 1/2" oil to a large skillet over high heat. When hot, quickly cook each tortilla for about 30 seconds on each side. Remove to paper towels to drain. Repeat for all tortillas. Place beef mixture in the center of each cooked tortilla and fold over. Working a few at a time, add the stuffed tacos back to the hot oil and fry until crisp on both sides, 1-2 minutes per side. Lift tacos from oil with a slotted spoon onto paper towels to drain. Repeat for all tacos. Gently open tops of tacos and stuff with cheese, onions, tomatoes and lettuce. Serve immediately.
These are my favorite tacos. I first ate them cooked like this at a Mexican restaurant in a small town in eastern Washington. You can stuff them with whatever you have on hand, chicken, fish or other vegetables.