If using the mix, mix in a large bowl according to the package instructions. Beat the masa, butter and salt in an electric mixer with the paddle attachment until it forms a ball. If using fresh dough, just add the butter and mix until a ball is formed. Using your hands, shape the dough into 8 discs, roughly 4 inches across and 1/2 inch thick. Grease a large skillet with cooking spray and set over medium-high heat. Cook the gorditas until lightly browned on each side, about 5 to 10 minutes on each side.

Fill a large skillet with enough oil to come about 1/2 inch up the sides. Heat over medium heat until hot enough that the oil bubbles when a small ball of dough is dropped in. Lower the gorditas into the hot oil – the oil should start bubbling. Fry the gorditas for about 5 minutes on each side, until golden brown and crisp. Transfer to paper towels to drain.

Saute the beef and onion in a large skillet over medium-high heat until the meat is brown – 8 to 10 minutes. Drain off the fat. Add the garlic, salt, cumin, pepper, hot pepper sauce, and tomato sauce. Cook for 5 minutes.

Split gorditas in half and set them on individual plates. Spoon the beef mixture over the bottom halves. Sprinkle with cheese, lettuce, tomatoes and sour cream. Lean the top half of the gordita at an angle on top of the beef mixture and serve.