Sardine Sandwich With Horseradish Cream | Saveur

Ingredients

• 1⁄4 cup rice-wine vinegar
• 1 tsp. sugar
• 1 tsp. black peppercorns
• 1⁄2 small red onion, thinly sliced
• 2 tbsp. mayonnaise
• 1 tbsp. prepared horseradish
• 1⁄2 tsp. fresh lemon juice
• 2 slices pumpernickel bread, toasted
• 2 leaves red-leaf lettuce
• 1 (4-oz.) can French sardines in oil, drained, plus 2 tsp. reserved oil
• 1 roasted red bell pepper, cut into thin strips
• Kosher salt and freshly ground black pepper, to taste