In a sizable bowl, mix the soy sauce, Worcestershire sauce, and 6 minced garlic cloves. Add the steak and let it marinade for 30 minutes at room temperature or overnight covered in the fridge (bring to room temperature before cooking).

In a skillet (cast iron would be ideal), heat a little olive oil over high heat.

Depending on thickness, add the steak and cook for 8 to 10 minutes on each side, or until an instant-read thermometer reads 125 to 130 degrees Fahrenheit and the steak feels like a loose fist to the touch.

The steak should be taken out of the pan and covered loosely with foil. Let it rest.

Add the mushrooms, onions, and final 3 tablespoons of garlic to the pan while the butter (if used) and any liquids are melting. Cook while frequently stirring until softened.

Red wine should be added to the pan to deglaze it and remove any food debris. Simmer for a few minutes or until most of the liquid has been absorbed. Get rid of the heat.

Either slice the steak and serve the onions and mushrooms on the side, or serve the steaks individually with the sauteed onions and mushrooms on top.