Prepare flour tortillas according to package instructions.

Chop the large onion.

Melt butter in a skillet over medium heat.

Add chopped onion to the skillet and cook until translucent.

Add refried beans to the skillet with the onions.

Cook and stir the bean mixture until heated through.

Spoon 1/4 cup of the bean mixture onto each tortilla near one edge.

Top the bean mixture with shredded Cheddar cheese.

Add 1 tablespoon of taco sauce to the cheese.

Fold the nearest edge of the tortilla over the filling.

Fold in both sides of the tortilla, envelope fashion.

Serve the burritos with additional taco sauce.