Place 1 cup stock in a pan and bring to the boil. Remove from the heat and stir in the couscous. Set aside for 5 minutes.
Place remaining stock in another pan and cook the zucchini and carrot until no moisture remains. Puree chick peas in a food processor with the egg.
Transfer chick peas to a bowl, stir in the couscous, vegetables, spring onions and coriander. Shape into 6 patties and barbecue, grill or cook in a non-stick frying pan. Serve the patties in rolls to make burgers with lettuce, tomatoes and a dollop of yoghurt.