Prepare marinade in a food processor or blender, combine all ingredients EXCEPT steak and Brussels sprouts; pulse until slightly smooth.
Place steak in a large zipper topped plastic bag; pour marinade on top.
Seal bag and turn to coat steak with marinade; refrigerate overnight or for at least 4 hours.
Preheat oven to 350 degrees.
Remove steak from marinade, reserving marinade.
Place the steak and Brussels in a large roasting pan and cook in the oven for 30 to 40 minutes, or until the brussels are tender and the steak is cooked to the desired doneness.
Place reserved marinade in a saucepan over medium-high heat; cook for 3 to 5 minutes then reduce heat and simmer for 8 minutes or until reduced and thickened; serve over steak.