Preheat your oven to 425°F.
Spread the Alberta Beef Bones on a parchment lined baking sheet and roast in the oven for 15 minutes.
Quarter your onions, and cut the carrots and celery into 2" pieces.
Remove the Alberta Beef Bones from the oven and add onions, carrots, celery, garlic and tomato paste. Roast for an additional 30 minutes, stirring occasionally until they are caramelized and browned.
Transfer the roasted Alberta Beef Bones and vegetables to a large stock pot, ensuring to scrape all of the tomato paste in. Then add the bay leaf, peppercorns, thyme, and parsley.
Add water, making sure the Alberta Beef Bones and vegetables are fully submerged. Slowly bring to a simmer (not a boil). Skim off any foam or scum that rises to the surface.
Reduce the heat just below a simmer and cook gently for 10-12 hours, skim the surface from time to time to remove impurities. Add cold water as needed to keep the bones covered.
Strain the stock through a fine sieve, discard solids.
Allow the stock to cool, then refrigerate or freeze in portion for future use.
