Open-Faced Turkey Sandwich

4 slices country or peasant bread 4 teaspoons mayonnaise 4 teaspoons Dijon mustard 1 cup trimmed arugula 2 thin slices red onion 12 ounces thinly sliced deli turkey 2 apples, each cored and cut into thin slices 4 slices Havarti cheese Coarsely ground black pepper (optional)

Preheat broiler with oven rack in middle position. Spread each bread slice with 1 teaspoon mayonnaise and 1 teaspoon mustard. Layer each slice with ¼ cup arugula, a few strips of onion slice, 3 ounces turkey, 4 apple slices, and 1 cheese slice. Place sandwiches on a baking sheet; broil 4 minutes or until cheese is bubbly. Remove from heat; sprinkle with pepper, if desired. Serve immediately.