Roughly chop onion, celery, and carrots. Sauté lightly in canola oil in a large stock pot until vegetables are tender. For lighter stocks (vegetable, fish) do not get any color on the mirepoix. If you want a darker stock (beef stock, chicken), sauté the mirepoix longer for caramelization. If you have additional vegetable scraps, you can add them at this stage. Be careful not to add anything that is too strong in flavor as that will overpower your stock. Good options include garlic, leeks, squash, zucchini, corn husks. Do not use bell peppers.
Add paste and stir to coat the mirepoix. Sauté for one to two minutes to caramelize.
Add wine (or some acidic liquid—can be red wine if doing a darker stock) and stir to loosen from the bottom of the pot the crusts of flavor developed during the caramelization.
Bouquet Garni, Bones, and Water
Add your herb sachet to the pot. Add meat bones to the pot. For darker stock, roast the bones beforehand for more color and richer flavor. Now add cold water to pot. This stops the cooking process and brings all ingredients to the same cold temperature together. Everything will cook consistently together as the temperature rises.
Simmer and Skim
Bring the stock to a low simmer, but do not bring it to a high boil. This is too harsh for the delicate stock and ends up clouding your final end product. Skim the stock of any scum or oil that rises to the surface with a spoon and dispose. Depending on the level of flavor for the stock, your simmering time will vary. For chicken stock, 2 – 6 hours is necessary. For vegetable and fish stock, do not simmer longer than 40 to 60 minutes.
Strain and Store
Strain the stock with a chinois or fine strainer, reserving the liquid. Stock can be stored for 2 – 3 days in your refrigerator or frozen for 3 months. Freezing the stock in ice cube trays can make it easy to pull a little stock for a quick glaze. When re-heating the stock, you can bring it to a slight boil and then reduce it to a simmer.