Step 1

Place beef, pancetta and 2 tablespoons pesto in a processor. Season with salt and pepper. Pulse until just combined (do not overprocess). Form mixture into 4 patties and chill while you cook the vegetables.

Step 2

Preheat the oven to 160°C.

Step 3

Heat a chargrill pan or barbecue over medium heat. Toss onion in a little oil and grill for 1 minute each side or until just cooked. Place in the oven to keep warm.

Step 4

Brush tomatoes with a little oil and season, then grill for 1 minute each side. Place in the oven to keep warm.

Step 5

Brush both sides of patties with oil. Cook on chargrill for 2-3 minutes each side until cooked through.

Step 6

Mix remaining pesto with mayonnaise.

Step 7

Top patties with cheese and place in oven for 1 minute or until cheese melts.

Step 8

Spread bread-roll bases with some of the mayonnaise mixture. Top with rocket, patties, onion and tomato. Drizzle with remaining mayonnaise mixture and top with remaining bread-roll halves