Let this cook over medium heat for 1 minute, then add grouper or whatever fish you like.
Let the fish cook until about 3/4 the way done, then put a little butter on top of fish and add blackening seasoning. When fish is done, put on a plate and move to the side and keep it warm.
Stir in lemon juice into pan drippings. If you need a little more butter and garlic, put some in pan. Then add green onions and mushrooms. Let cook until green onions and mushrooms soak up lemon juice or until done.
Taste mushroom and if it makes you make a sour face, then you know it's done. If not, add a little more lemon juice.