Beef and Mushroom Blended Caramelised Onion Rings, Rocket and Camembert Cheese Burger | Blenditarian

Ingredients

• 150g mushrooms, grated
• 350g beef mince
• 1 egg
• ⅓ cup breadcrumbs
• 1 tbsp Worcestershire sauce
• 1 tsp salt
• ¼ tsp white pepper
• 2 tbsp vegetable oil
• 4 Pane di Casa buns
• 2 large Spanish onions
• 2 tbsp balsamic vinegar
• ¼ cup olive oil
• 1 tbsp brown sugar
• 1 wheel camembert cheese, sliced
• 2 cups rocket
• Freshly ground black pepper