Any bits of left over vegetables and a few pepper corns and herbs. Beetroot is not so suitable unless you're looking for purple stock! Things like the green of the leek that you left out of your white winter vegetable soup are ideal. The most common vegetables used are carrots, white turnip, onions, celery, mushrooms and fennel. Parsley is the most used herb but feel free to experiment.

Bung them all into a big sauce pan with cold water and bring up to the boil, then reduce heat and simmer for about an hour. Strain through a sieve. This freezes perfectly. We use old milk cartons because you can cut them open to get it out and defrost quickly.