Halve half of the grape tomatoes and place on a baking tray, cut side up. Cook at 100C for 2 hours. Cool. Reserve remaining grape tomatoes until ready to serve.
Meanwhile, in a bowl, combine mince, onion, garlic, tomato paste, salt and pepper. Form into small burgers and refrigerate until use.
For jam, simmer all ingredients for 10 minutes. Stand to cool.
When ready to cook, halve rolls and place under a grill to toast. Spread with butter (optional).
Grill lamb burgers and bacon for 7-8 minutes, until cooked.
Slice the remaining grape tomatoes. Spread barbecue sauce on 12 roll halves (the bases) and top with a cos lettuce leaf. Layer with oven-dried grape tomatoes, burger, bacon, tomato jam and a slice of fresh grape tomato.
Top with remaining rolls (lids) and serve garnished with any remaining fresh grape tomato halves.