Lightly score the meat on both sides in a diamond pattern.
Put all the marinade ingredients in a ziploc bag.
Add the meat to the bag and massage the marinade in.
Let marinate for 1-2 days.
Heat a bbq to high temperature.
Once hot, turn down to 350°F, remove the meat from the bag, let the marinade drip off, and place on the bbq.
Let cook for 7 minutes, flip over and cook for another 7 minutes.
Remove from the bbq and slice against the grain.
Serve with horseradish and mushroom sauce.