Heat three gets underway, which means six new amateur cooks have left their home kitchens ready to compete for one of four coveted MasterChef aprons. The Signature Dish round features a meal they would serve to impress friends or family, before the next challenge requires them to make an authentic salade niçoise. Previous MasterChef winners Jane Devonshire, Dr Saliha Mahmood Ahmed and Thomas Frake assess their efforts