Mix together the guacamole ingredients. Season and set aside for the moment.
For the burgers, heat the oil in a pan and sauté the onion and the remaining 2 garlic cloves for a few minutes. Allow them to cool, then tip into a bowl and add the parsley, mince and chilli powder, the whisked egg and breadcrumbs. Season and mould into 4 burgers.
Brush the burgers with oil and place on a grill for about 4 minutes each side until cooked through. Cook the pepper and onion slices on the barbecue, until softened.
Serve in toasted buns with lettuce, the peppers and onions, and some guacamole.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.