Start by heating a skillet over medium-high heat. Add a teaspoon of olive oil, then toss in the ground beef. Brown it until fully cooked. This takes about 5-7 minutes. Break it up into small pieces with a spatula and drain excess fat.

Sprinkle the taco seasoning over the beef. Pour in the beef broth. Mix everything together, allowing the seasoning to meld with the beef. Let it simmer for about 5 minutes, stirring occasionally.

While the beef simmers, warm tostada shells in a separate pan on low heat. This step is crucial as it makes them more pliable. Avoid overcooking them; you want them just warm enough to handle.

Grab a flour tortilla. Start by adding a layer of the beef mixture in the center. Follow with a dollop of nacho cheese sauce, then sprinkle some shredded cheese on top. Next, place a tostada shell over the cheese. Spread sour cream over the tostada and top with diced tomatoes, lettuce, and red onion.

Carefully fold the edges of the flour tortilla towards the center, covering the filling. Create pleats as you go to form a sealed parcel.

Heat a skillet over medium heat. Place the wrapped side down on the skillet. Cook until the bottom is golden brown, about 3-4 minutes. Flip and repeat for the other side.