Flank steak should be cooked rare to medium rare for best flavor.
Fill 1/3 cup with prepared horseradish that has been squeezed of excess liquid and combine in a small bowl with vegetable oil. Heat broiler.
Cut flank steak into 4 equal pieces. Generously season steaks on both sides with coarse salt and ground pepper. Place on broiler pan; pat horseradish mixture on top of steaks.
Broil until crust is slightly browned and steak is cooked to desired doneness, 5 to 7 minutes for medium-rare.
