In a large skillet, melt butter over high heat. Throw in mushrooms, garlic and green onions and cook, stirring occasionally until mushrooms are nice and golden.
Pour in wine and stir, scraping bottom of the pan. Allow to cook for several minutes or until liquid is reduced bu at least half.
At the end, add 1 tablespoon butter and stir into sauce. Add parsley and stir together. Don't be afraid to splash in a little more wine if needed.
Fry a steak in a separate skillet until medium rare.