In a large skillet over medium heat, add the ground beef. Use a spatula to break it up as it cooks. Once browned, drain any excess fat, then add the Old El Paso seasoning and water. Stir well and let it simmer for about 5 minutes until thickened.
While the beef is cooking, take your sourdough bread slices and spread softened butter on one side of each slice.
On a cutting board, place one slice of bread butter-side down. Layer with a generous amount of shredded cheddar cheese, followed by a scoop of the seasoned ground beef. Top with another layer of cheddar cheese and finally place another slice of bread on top, butter-side up. Repeat this process for all sandwiches.
In the same skillet used for the beef, carefully place the prepared sandwiches over medium heat. Cook for about 3-4 minutes on one side until golden brown, then carefully flip and cook the other side for an additional 3-4 minutes.
Once cooked, remove the sandwiches from the skillet and let them cool slightly. Cut them in half and serve with your favorite taco toppings.
