Step 1: In a large skillet, brown the ground beef over medium-high heat, breaking it apart with a spoon. Drain any excess grease.
Step 2: Add the taco seasoning and 1/4 cup of water to the ground beef. Stir well and simmer for 5-7 minutes, or until most of the liquid has evaporated and the beef is well-seasoned.
Step 3: Warm the nacho cheese sauce in a small saucepan over low heat or in the microwave until smooth and pourable.
Step 4: Lay one large flour tortilla flat. Sprinkle about 1/4 cup of the shredded cheese blend evenly over one half of the large tortilla. Place one smaller flour tortilla directly on top of the shredded cheese.
Step 5: On the smaller tortilla, spread about 2 tablespoons of warm nacho cheese sauce, then add 1/4 of the seasoned ground beef. Top the beef with 2 tablespoons of sour cream and another 1/4 cup of shredded cheese.
Step 6: Carefully fold the smaller tortilla into a tight burrito, tucking in the sides. Then, fold the large tortilla over the burrito, creating a sealed package.
Step 7: Heat vegetable oil or butter in a large non-stick skillet or griddle over medium heat. Place the assembled Quesarito seam-side down in the hot skillet.
Step 8: Cook for 3-4 minutes per side, or until golden brown and crispy, and the cheese is melted. Press down gently with a spatula during cooking to ensure even browning and melting.
Step 9: Remove from skillet, slice in half if desired, and serve immediately. Repeat with remaining ingredients.