1. You can use pickled onions for this sandwich, or you can quickly make your own by slicing a red onion finely. Bring ¼ cup cider vinegar, 1 tsp sugar and 1 tsp fresh peppercorns to a boil. Strain on to the onions and leave to pickle for 30 minutes.
2. Make a horseradish mayo by mixing 2 Tbsp horseradish, 1 tsp hot mustard, 2 Tbsp mayonnaise, a little lemon zest and juice, and a little salt and pepper.
3. Toast 2 pieces of bread and spread with the horseradish mayo. Add some red lettuce leaves and a few coriander leaves. Place good-quality canned sardines on top, garnish with slices of roasted red pepper, the pickled onions, a sprinkle of sea salt, and fresh black pepper.

Check out Warren's other deli sandwiches

• The Cubano (ham & roast pork)
• The Roxy (chicken)
• The Monterey Manwich (pork)