Although over the years we have made several different versions of veggie and bean burgers, patties and cakes, nothing is quite like a grilled portobello mushroom burger. It is the simplest, most natural and delicious piece of food you can put inside a burger bun. It is big, chewy and actually strikingly burger-looking, and when heated it releases moisture and becomes all flavourful and juicy. We like to top our burgers with mashed avocado, fresh tomatoes, sprouts and some kind of fruity salsa. Here we have replaced the salsa with peaches that are grilled with the mushrooms.