Brown hamburger and onions; drain. Add taco seasoning (prepare as directed on taco seasoning package). Add refried beans. Mix soup with 4 ounces of sour cream. Spread enough of the sour cream mixture to cover the bottom of a casserole dish.
Put meat into tortillas. Wrap like a burrito and place seam side down in casserole dish. Put the remaining sour cream on top of the burritos. Sprinkle cheese over top and bake, uncovered, at 350 degrees F. for 20 to 30 minutes. You can garnish with chopped green onions, chopped tomatoes, remaining sour cream, and Picante sauce if you like.