Vegetable stock is an excellent substitute for chicken stock, and is a must for all types of vegetarian cooking.
To make 4 cups of vegetable stock we used 2 large onions, 2 medium carrots, 3 stalks of celery, 1 whole bulb of garlic, 10 peppercorns, and a bay leaf.
1. Chop the vegetables into large chunks rather than small dice. The stock should simmer for a full hour--and over time, the stock will take on all of the flavors of the vegetables.
2. Remove and discard leaves from the celery stalks. Celery leaves, especially those on the outside of the bunch, are bitter and should not be added.
3. Slice the celery into large pieces.
4. Peel and chop the carrots into large pieces. If you'd like to preserve more of the carrots' nutrients, don't peel them. Instead, scrub them under cold running water, then chop into large pieces.
5. Garlic is the base flavor for this stock, so we use a whole bulb of garlic.
Break up the bulb into individual cloves. Peel the garlic using the method shown in Peeling Garlic. There's no need to chop the garlic.
6. Once all of your ingredients have been prepared, combine them in a large stockpot--large enough to hold the covering water.
7. Add aromatics to the vegetable medley. We used peppercorns and a bay leaf. You can also add herbs or scraps leftover from other dishes. Potato scraps will help thicken the stock a little. Parsley, thyme, or rosemary stems are other good additions. If you're planning on using this stock in an Asian recipe, try adding fresh, peeled ginger.
8. Pour enough water into the stockpot to completely immerse the vegetables.
An interesting trick to making delicious, thick vegetable stock is to use potato water strained from mashed potatoes along with (or instead of) water!
9. Turn the stove to a high temperature, and bring the stock to a quick boil. Once the water has begun to boil, turn the stove down to low. Allow the vegetables to simmer for an hour. Any longer than an hour and the vegetables will begin to turn mushy and lose their vibrant flavor.
10. Strain your stock through a fine mesh straining device. Cheesecloth placed in a colander would also work well.
11. The stock should be light in color, sweet, and translucent. If you want a darker colored stock, caramelize the onions and carrots (see Caramelizing Onions) before placing them in the stockpot. Alternately, roast the vegetables until caramelized, then add them to the stockpot.