Pre-heat oven to 350º (gas mark 4).
Mince the liver and onion together, preferably in a food processor.
Put in a bowl and stir in the suet, breadcrumbs, sage and seasoning to taste.
Form the mixture into 12 balls with floured hands and place in a well greased, shallow, ovenproof dish.
Pour the stock into the dish.
Cover and bake for about 30 minutes.
Uncover and continue cooking for a further 10 minutes to brown the faggots.
The remaining gravy may then be thickened, if preferred.