Instructions

Serving size: 2

1. Dry the steak at room temperature and season it generously with salt.
2. Heat a large skillet, preferably cast iron, over medium-high heat. Add olive oil, once the oil is hot, carefully place the steak in the pan. Cook the first side for about 2 minutes, until you get the golden-brown crust.
3. Turn the steak and cook the other side for about another 2 minutes.
4. Add crushed garlic, thyme and butter.
5. Tilt pan toward you so that butter pools on one side, and use a large spoon to continually baste steak with butter. Continue until butter is no longer bubbling, it smells nutty and is beginning to brown, about 1 minute. Transfer meat to a cutting board and let rest 5-10 minutes. For medium-rare, your steak should reach an internal temperature of 125°–130°. Keep in mind, the meat will continue cooking while resting.
6. Discard the thyme and garlic. Add the mushrooms. Cook them in the pan sauce.
7. Add the red wine and a splash of heavy cream. Taste and see if it needs more salt and pepper.
8. Spoon the mushrooms and red wine sauce over the sirloin. Garnish with couple sprigs of thyme (optional).

For the best result, it important to let the beef comes to a room temperature. Also dry it to get rid of the moisture for proper browning.

Source: http://www.letscooksomefood.com/butter-basted-wagyu-sirloin-steak-with-mushrooms-and-red-wine-sauce/