Big Game Week: Pastrami and Aged Cheddar Football Panini

INGREDIENTS

• 1/4 cup sour cream
• 2 tablespoons mayonnaise, regular or reduced-fat
• 1 tablespoon prepared horseradish
• 1 teaspoon finely grated onion
• 1/2 teaspoon Worcestershire sauce
• Salt and pepper
• 8 slices pumpernickel bread
• 1/4 pound thinly sliced pastrami
• 2 tablespoons sliced peperoncini*
• 4 ounces shredded sharp aged cheddar cheese