Heat oven to 400°F In 10-inch skillet, melt butter over medium heat. Stir in taco seasoning mix. Add beef strips; cook 5 to 6 minutes, stirring occasionally, until desired doneness; drain.
Meanwhile, place refried beans in microwavable dish. Microwave uncovered on High 2 minutes, stirring once or twice.
Spread each tortilla with refried beans to within 1/4 inch of edge. Top each with beef, Cheddar cheese and onions. Roll up, folding in sides. In ungreased 13x9-inch (3-quart) glass baking dish, place burritos with seam sides down. Pour enchilada sauce over burritos. Sprinkle with Mexican cheese blend.
Bake uncovered 7 to 12 minutes or until burritos are thoroughly heated and cheese is melted.