Preheat oven to 425° F.

Combine carrots, celery, onions, leeks and garlic in a bowl and toss with olive oil. Spread out on a sheet pan and roast in the oven for 20 to 25 minutes, (stirring once or twice to distribute the browning) until they are starting to caramelize around the edges.

With a length of kitchen twine, tie sprigs of herbs together with bay leaves into a bundle. This is your bouquet garni.

Pour 4 quarts of cold water into a soup pot and add roasted vegetables, bouquet garni, cloves and peppercorns. Bring pot to a simmer over medium-low heat. You should only see a few bubbles intermittently rising to the surface. Cook, uncovered, for 2 hours. During the cooking process, add a little more liquid to the pot if needed to keep the ingredients submerged.

Strain the stock, pressing hard on vegetables to squeeze out the juices. Discard vegetables.

Season stock with salt and pepper.

Important note: With a batch of stock this size it is important to cool it as quickly as possible. Here are 2 good methods:

1) Place the pot in a bath of ice water in your sink, and stir occasionally until it is cooled, then refrigerate.

2) Let the stock cool for about 15 minutes, then pour into individual heat-proof jars and put them directly in the refrigerator. Leave an inch of room at the top of the jar to allow for expansion when freezing.

You can store the stock in the refrigerator for several days. If you are not going to use it within that period, freeze it for up to six months.