Place steak in a large ziplock bag

Combine all marinade ingredients in a bowl and whisk together to blend

Pour marinade into the bag with the meat

Marinate steak in refrigerator for 3-4 hours

Preheat grill or grill pan on medium-high heat

Brush the grill with vegetable oil before cooking to desired doneness (For medium rare, cook about 6-8 minutes per side)

Remove from heat and allow meat to rest for 5 minutes prior to slicing (cut across the grain of the meat thinly using a sharp knife)

Place first 9 ingredients for the mushroom sauce in a 2-quart saucepan

Bring sauce to a boil, reduce heat to a simmer, and cook for about 5 minutes

Combine cornstarch with water in a small bowl to make a slurry

Drizzle the slurry slowly into the simmering liquid to thicken

Bring back to a simmer

Serve steak with mushroom sauce