Do not rinse the bones, but place them directly in a large oiled roasting pan. If desired, brush them quickly with tomato paste (this adds more colour and flavour to the stock).
Roast the bones, turning once with a sturdy pair of tongs, until the bones caramelize, approximately 1 1/2 hours. Do not let them burn, or your stock will be bitter.
Meanwhile, prepare your mirepoix: roughly chop the onion, leek, celery and carrots and toss them with a little oil.
Place them in another oiled roasting pan or sheet, and roast alongside the bones until lightly caramelized, approximately 25 minutes.
Remove bones from oven and transfer to a large stock pot. There will be a pool of fat at the bottom of the pan which you can drain off before deglazing the pan, or you can add it to your stock. It will only add more flavour to the final product.
Add a few cups of cold water to the roasting pan to deglaze it, and use a solid spatula to lift off the remaining food particles on the bottom of the pan and all the flavour they bring. Add mixture to the pot with the bones.
Add roasted mirepoix, herbs, garlic, peppercorns and bay leaves to the pot of bones. Fill pot up with cold water until the ingredients are just barely submerged and place on stove burner.
Bring stock to a boil -- and reduce heat immediately. Simmer slowly for 6-8 hours, occasionally skimming excess oil or scum off the top. You don't need to babysit it much, just make sure it is at a temperature where it will will simmer, but not boil.
Using a sturdy spider skimmer, dip into the large pot and fish out the bones. Allow them to drain a bit and then toss them in the garbage. (I usually haul my garbage bin right over to the stove, to make things easier.) When you have fished out all the large ingredients, strain the broth through a fine sieve into a sturdy bucket or another pot.
If you have the time and patience, strain the stock a second time through a cheesecloth to further remove impurities.
When it is at room temperature, divide among sanitized covered containers for storage. Mason jars work well for freezing, but be sure to leave at least 1 inch of head space to allow for expansion.
Don't worry if a thin layer of fat forms at the top of your containers. This helps preserve the stock and can easily be removed with a spoon before using.
Stock can be stored for up to one week in the refrigerator or frozen for 3-4 months.