In a non-stick frying pan, fry the onion for a few minutes until soft. Add the salad onions or leek and carrots, and cook for 3 minutes till softened. Set aside to cool.
In a mixing bowl, add the cheese, half of the breadcrumbs, one egg, mustard powder and herbs. Stir in the fried veg mixture till combined.
Pour the second beaten egg onto a shallow plate, and the rest of the breadcrumbs on another. With floured hands, shape the vegetable mixture into sausage shapes. Dip each sausage into the egg and then roll in the breadcrumbs.
Heat the oil in a frying pan and shallow fry the sausages in batches for 6-7 minutes or until they are well cooked and golden.
For best results, shape the sausages, wrap them individually in cling film and place them in the fridge to firm up for at least half an hour.
The mixture is suitable for freezing before cooking.
Try substituting other vegetables such as aubergines, courgettes, swede and spinach.