INGREDIENTS

• 4 rolls of your choosing that are not too crusty
• 1 pound 85% lean ground beef
• Fine sea salt
• Freshly cracked black pepper
• 4 slices prosciutto di Parma or jambon de Bayonne
• 2 ounces grated Gruyère
• 2 tablespoons Dijon mustard
• ½ teaspoon whole-grain mustard
• ¼ cup mayonnaise
• 4 leaves Green Leaf or Romaine lettuce
• 4 slices beefsteak tomato (from 1 large tomato)
• A handful of cornichons (optional)
• 4 6-inch wooden skewers (optional)

PROCEDURE

1. Heat a 9-inch non-stick skillet on medium heat.

2. Slice buns horizontally and place 4 of the halves, cut-side face-down in the skillet. Toast approximately 7 minutes or until golden brown and slightly crisp. Set aside and repeat with the remaining buns. Wipe out crumbs from pan and return to medium heat.

3. Season beef with salt and pepper to taste. Form into 4 burger patties, and wrap each patty in 1 slice of prosciutto. Place each burger prosciutto-seam-side-down in the skillet. Cook burgers approximately 5 minutes on each side for medium doneness (140° to 145°F in the burger's center), using a wooden spatula to flip the burger once during cooking. In the last 3 minutes of cooking on the second side, top the burgers with the shredded Gruyère cheese, and tent loosely with aluminium foil to melt the cheese.

4. While the burgers are cooking, use a small whisk to combine the Dijon mustard, grain mustard, and mayonnaise with salt and pepper to taste in a small bowl.

5. To assemble the burgers, smear both sides of the bun with the homemade Dijonnaise. Rip each lettuce leaf in two, and place both pieces on the bottom of the bun. Top with a burger, and then a slice of tomato. Season the tomato with salt, and top with the top of the bun. Place a cornichon on a 6-inch wooden skewer, and use that to hold the burger together.