Assemble the taco filling. Melt butter in a large skillet over medium-high heat. Cook, stirring frequently, until the ground beef is browned. Drain the excess grease after the beef has browned. To the pan with the beef, add the taco seasoning and 1 cup of water. Stir thoroughly. Bring to a boil, then reduce to a low heat and continue to cook for 8 minutes. Take the pan off the heat.

Heat a clean frying pan or griddle over high heat and shred the cheddar cheese. Apply a thin layer of oil to the bottom.

Make the corn tortillas ready for frying. Warm 2 or 3 tortillas in the microwave for 20 seconds in batches. Place the open tortillas on the griddle over medium heat. 1 tablespoon of cheese on one half of each tortilla, followed by 2-3 tablespoons of beef filling, followed by 1 more tablespoon of cheese. If using additional fillings, combine them with the beef.

After 1 minute, gently fold the tortilla over to close the taco. Cook for 2 minutes before flipping and cooking for another 2-3 minutes, or until golden brown. Transfer the fried tacos to a plate lined with paper towels. Cover loosely with foil to keep warm while you prepare the rest of the tacos.