Deihl's Roast Beef Sandwich - The Local Palate

Ingredients

• Note: Start pickling onions a week before making the sandwich.
• 1 cup red wine vinegar
• 1 cup red wine
• 2 tablespoons sugar
• 2 tablespoons fish sauce
• ½ teaspoon marjoram
• ½ teaspoon juniper berries
• 2 whole cloves
• ½ teaspoon allspice
• ½ teaspoon fennel seed
• ½ tablespoon coriander
• 1 bay leaf
• 1 dried chile
• 4 cups sliced onions
• 2 tablespoons mayonnaise
• 2 tablespoons sour cream
• ½ cup prepared horseradish
• ¼ cup Dijon mustard
• 1 tablespoon Worcestershire sauce
• Salt and pepper
• 4 potato bread rolls
• 2 cups arugula
• ½ cup red wine pickled onions
• 2 tablespoons olive oil
• Salt and pepper to taste
• 6 ounces horseradish dijon
• 1¼ pounds roast beef