Add the beef to a large non-stick pan and cook over medium high heat, breaking up the meat into tiny pieces as it browns. You won’t need any extra oil as browning ground beef renders out enough fat on its own.
After the beef browns and cooks through, add the flour, tomato paste, taco spices, and 1/4 cup water. Stir to combine and bring to a simmer, stirring occasionally, until the sauce thickens slightly. Remove from the heat.
While the beef is cooking, be sure to warm up the nacho cheese and refried beans.
Heat up the tortillas by wrapping in slightly damp paper towels and microwaving for 30 seconds. Top half of the tortillas evenly with warmed nacho cheese, spreading to the edges.
Top with the remaining tortillas, gently pressing them together to make a cheesy tortilla sandwich. Evenly fill the tortillas with refried beans, the seasoned beef, sour cream, and shredded cheddar.
Wrap into burritos by folding in the sides, then the bottom of the tortilla, then tucking and rolling. Slice in halves and enjoy while warm!