Add the 1 tablespoon of butter and olive oil to a skillet and heat. Saute the mushrooms, onion and garlic until garlic starts to brown then transfer this to a clean bowl and set aside. (add in the asparagus the last minute of sauteing the mushrooms.) Add the wine to the skillet and deglaze the bits that have stuck to the bottom. Let cook down for about 3 minutes.
*If you do not have leftover steak then take a raw piece of steak and cut into thin slices/pieces, toss this with a little flour and brown this in some extra oil/butter mixture before cooking your mushrooms.