Beef Burger with Roast Tomato and Caramelised Onions

Ingredients

• 400 grams lean beef or lamb mince
• 1 onion, finely chopped
• 1/4 cup fresh breadcrumbs
• 2 tablespoons finely chopped parsley
• 1 egg, lightly beaten
• 1 clove garlic, crushed
• 4 damper bread rolls, split, toasted
• 4 oak lettuce leaves
• 2 slices prosciutto, halved, baked until crisp
• tomato sauce, to serve
• 2 roma tomatoes, quartered
• 1 tablespoon olive oil
• 2 red onions, sliced
• 1 tablespoon white vinegar
• 2 teaspoons sugar
• 2 tablespoons water