Now that I've given the recipe for chicken stock, I've been asked how to make vegetable stock. For a comprehensive discussion of vegetables and their qualities in stock, I highly recommend the section on stocks by Deborah Madison in The Greens Cookbook. Madison uses many different vegetarian stocks, providing recipes for four general stocks and many individual stocks to complement the flavours of particular soups or stews.
But for an all-purpose stock which provides body and flavour to a dish without dominating, and is made from readily available ingredients, here's my recipe.
Warm a good drizzle of olive oil in a large soup pot. Add the vegetables as they are prepared, so that each has a few minutes to sauté before the next is added. Add the aromatics, salt, and 3 litres of cold water and bring to the boil. Skim off any scum that rises to the surface, then lower the heat and simmer for 45 minutes to an hour. Strain.
For a stronger flavour, return it to the pot and reduce further. Taste for salt.
Pour into small containers. Cool, then store in the freezer. I freeze my stock in single-cup portions, easy to measure when making a soup, stew or risotto at a later date.
(Local: onions, garlic, celery, carrots, fennel, parsley, chard, lettuce, mushrooms, bay leaves, olive oil. Not local: salt, peppercorns.)