1 pound beef (flank or skirt steak)
4 rolls or 8 slices bread
1/2 cup plain yogurt
1/2 lemon, juiced
1 tablespoon prepared horseradish
2 cups arugula
Sea salt and fresh ground pepper to taste
Grill steak over hot coals or cook in a sauté pan until desired doneness. Chill the cooked steak in the refrigerator. Slice the chilled steak against the grain into thin strips.
Toast the bread.
In a small mixing bowl, combine the yogurt, lemon juice and horseradish. Taste the horseradish sauce and adjust seasoning with salt and pepper.
Assemble sandwich by layering steak, arugula and horseradish sauce on the toasted bread.