Preheat oven to 350° F. Grease an 11x7x2" baking dish.
Fry onion in butter until tender. Stir in flour and salt until smooth; add milk and cook until thickened. Cook 1 minute more. Remove from heat; stir in sour cream.
Place wild rice in baking dish. Top with asparagus, sauce, cheese and bacon. Bake 30 minutes.Servings: 4