1Finely chop mushrooms by hand, or alternatively, pulse in a food processor until finely chopped.
2Heat 1 tbs oil in a large frying pan over medium heat. Add onion, garlic and spices. Sauté for 5 minutes or until softened. Add mushrooms, increase heat to high and cook for8 minutes or until moisture has evaporated. Set aside to cool for 10 minutes. Drain any excess moisture and transfer to a bowl.
3Transfer 1/2 cup parsley and 1/2 cup mint leaves to a bowl, set aside. Finely chop remaining herbs. Add mince, egg, breadcrumbs and chopped herbs to mushroom mixture. Season, mix well to combine. Shape mixture into 4 patties (about 9 cm diameter and 2cm thick). Place onto a tray, cover and refrigerate for 1 hour if time permits (this helps hold patties together when cooking).
4Heat remaining oil in a large non-stick frying pan over medium heat, alternatively preheat a barbecue flat-plate on medium. Add patties and cook, for 5-6 minutes on each side or until just cooked through.
5Spread bun bases with tzatziki, top each with reserved herbs, tomato, pattie and cucumber. Sandwich together with burger top. Serve with lemon wedges.