Pulse the mushrooms in a food processor, until more finely chopped. Transfer to a bowl.
Grate zucchini/courgette and drain in kitchen towel. Add to the mushrooms.
Heat 2 tablespoons of oil in a large pan over a medium heat and add the shallot. Cook for about 2 minutes, or until tender.
Add mushrooms and zucchini/courgette and cook also until tender. Transfer to a bowl and add the cheese and quinoa. Season with salt and pepper and allow to cool completely.
Then stir in the egg and breadcrumbs, cover and refrigerate for about 1 hour until firm.
Heat the remaining oil in a large pan over a medium heat. Shape the mixture into six 1-inch-thick patties and cook in batches until golden brown, about 3 minutes each side.
To serve, spread yoghurt garlic sauce onto the buns, top the burgers with sliced red onion and tomato, and sandwich in buns.
Andy’s Sugar Safe® Tips