Sauce ingredients:
1/3 cup red burgundy (or your choice) drinking wine
1-1/2 cups thinly sliced button mushrooms
4 tablespoons minced onions  
2 clove garlic, crushed  
1/4  teaspoon salt  
2 teaspoons lemon juice  
1 teaspoon Worcestershire sauce
1 tablespoon light soy sauce  
2 sticks butter or margarine
1 tablespoon dried parsley flakes

In a large enough fry pan, heat pan 
just under medium heat, pour in the wine (it should sizzle) and heat it until it evaporates leaving only 1/2 the volume, add and melt the butter, brush melted butter on one side of each cut tenderloin then set them aside. Using the same heat, add the mushrooms, onion, garlic, salt, lemon juice, worcestershire and soy sauce to the remaining butter in the fry pan, stir often and cook until mushrooms are tender then stir in parsley; keep sauce warm. 

Steak Method:
You will need 1-1/2  lb beef tenderloin, cut into 8 slices. You could also use less expensive steak meat like; Rib eye, Flank (London Broil), Sirloin.
Preheat oven broiler placing oven rack one notch above the middle. Broil steaks  4-/½ minutes on each side or less, no more then medium done. 
Note: When broiling it is very important to leave the oven-door cracked open or meat will not broil properly, it will bake, get tough and dry out. Cooking on an outside grill is optional. Serve with mushroom-butter sauce to spoon over steaks and/or mashed potatoes.

Serves 4