- Heat 2 tablespoons olive oil in a frying pan, add mushrooms and onion and stir-fry over a medium heat for 5 minutes, until the pan juices evaporate and the mushrooms are lightly browned. Purée half this mixture in a food processor.
- Place cooked mushrooms and mushroom purée in a bowl with the garlic, egg and fresh breadcrumbs.
- Season with salt and pepper and mix well to combine. Divide mixture into four and shape into patties.
- Heat 2 tablespoons olive oil in a frying pan, add mushroom patties and cook over a medium heat for 4 to 5 minutes on each side. Drain on paper towels.
- At the same time, toast burger buns and place bases on serving plates.
- Top each with salad and a mushroom patty, then top with the bun lids. Serve with chutney, if desired.