Heat oven to 425 F/ 218 C
Lay the bones out on two trays with a rack and roast until golden brown, about 40 minutes, flipping halfway through.
Place the bones in a large pot. Flip the racks on the trays and add enough water to submerge the racks. Place in the oven for 5 minutes.
Remove the racks and use a wooden spoon to remove the fond. Add this to the bones and cover with cold water.
Bring this up to a simmer on high heat, and once bubbles come up pull the pot half way off the burner for a convection simmer. Use a spoon and a bowl of water to remove all the fat and impurities that float to the surface.
Place the pot back on the burner and lower the heat so that it is just at a simmer. Let this cook for 3 hours.
Add the carrots, onions and celery to the stock and cook for another 45 minutes.
Turn off the heat and add the thyme, peppercorns and parsley stems.
Strain the stock through a colander into a large bowl, then double strain to remove any small bits.
Fill your sink with ice water and place the stock in the large bowl to cool, then place in the fridge
*Notes
Putting water on the tray and rack will not only remove the flavorful fond, but it makes cleaning the pans way easier, just make sure you clean them while they are still warm.
A convection simmer will push all the impurities off to one side of the pot allowing you to easily remove all the fat and impurities. Plus it will prevent the fat and impurities from emulsifying which would create a cloudy stock.
Using a bowl of water not only gives you a place to put the impurities, but allows you to clean the spoon so that you don’t reintroduce them into the stock.
Cooling the stock to under 70 degrees fast will prevent bacteria from spoiling the stock.