Place a wooden spoon over two glasses or bowls to create a bridge.
Heat a non-stick skillet on medium heat. Place a small mound of shredded cheese in an even circular layer. Once the cheese begins to crisp up, flip over and cook for a few more seconds. Once it looks more firms, carefully lift it off with a spatula and place it over the horizontal spoon handle to form a taco shell. once it hardens, set aside and continue making cheese shells.
To make the filling: in the same pan, cook the ground beef, onion, and taco seasoning until browned. Drain any excess fat.
To serve: place the beef in the cheese shells and top with lettuce, tomato , jalapeño, sour cream, and lime.