Prepare Horseradish Sauce (see recipe below).
Using a sharp knife, score the surface of the flank steak wit shallow diagonal cuts at 1-inch intervals, making diamond shapes. Repeat on other side of steak.
In a large resealable plastic bag, combine lemon juice, mustard, Worcestershire sauce, garlic, and hot pepper sauce. Add prepared flank steak. Seal bag and turn to coat. Refrigerate at least 8 hours or overnight, turning steaks occasionally.
Preheat Barbecue grill. Remove steak from marinade; discard marinade. Place steak onto hot grill. Cover barbecue with lid, open any vents and grill until steak is medium rare or until the internal temperature reaches desired temperature on your meat thermometer (see below). NOTE: This steak is best cooked rare to medium rare.
Rare - 120 degrees F
Medium - 130 degrees F
What constitutes rare and medium-rare cooked meat? To satisfy government home economists, the Beef Council says rare beef means an internal temperature of 140 degrees F. Well, that is ok if you like well-done and dry meat. If you like moist, rosy meat (like I do), rare begins at 120 degrees and starts to become medium rare at 125 or 130 degrees. To cook your meat properly, you must purchase and use a good instant-read digital meat thermometer.
Remove from heat and let steak rest 5 minutes before slicing. With a sharp knife, slice steak thinly against (diagonal) the grain. Place on a platter or individual dinner plates and serve with Horseradish Sauce.
Makes 4 servings.
In a small bowl, combine mayonnaise, sour cream, Dijon mustard, green onions, and horseradish; cover and refrigerate until ready to serve.
Grilled Flank Steak with Horseradish Sauce Recipe: https://whatscookingamerica.net/Beef/HorseradishFlank.htm