Step 1

Cook garlic in oil, stirring frequently. Add soy sauce, rosemary and mustard. Remove from heat and stir in sherry, apple cider and vinegar. Allow to cool completely.

Step 2

Place top sirloin roast in a large plastic zippered bag and pour marinade over roast. Close bag and marinate roast in refrigerator 6 to 8 hours, or overnight.

Step 3

Remove roast from refrigerator and pat dry with paper towels. Discard marinade and preheat oven to 450°F232°C. Season roast with kosher salt and black pepper and place in a shallow roasting pan fitted with rack. Roast 15 minutes in preheated oven, then reduce heat to 350°F177°C. Cook approximately 1 1/2 hours to reach medium doneness (135-140°F58-60°C).

Step 4

Remove roast from oven, tent loosely with foil and rest 15 minutes before carving.