Preheat oven to 400°F. Rub a little bit of olive oil over the stew meat. Place stock bones and stew meat into the Cooking Vessel.
Once the oven has preheated, place the Cooking Vessel into the oven. Roast in the oven for about 45 minutes. Turn the bones and meat pieces half-way through cooking, until nicely browned.
When the bones and meat are nicely browned, remove theCooking Vessel from the oven and place it into the Cooking Base.
Add carrots, onions celery tops, garlic, parsley, bay leaves and peppercorns into the Cooking Vessel.
Fill with cold water, 2 inches over the top of the bones (about 8-9 cups of water).
Close the lid. Select-SLOW COOK and set the time to 12 hours. Press START.
From time to time check in on the stock and use a large metal spoon to scoop away the fat and any scum that rises to the surface.
Do not stir the stock while cooking. Stirring will mix the fats in with the stock, clouding up the stock.
Once the cooking cycle is complete, open the lid.
Strain the beef stock through strainer.
Serve immediately or let cool to room temperature then chill in the refrigerator. If you plan to freeze the stock, however, remove and discard the fat, pour the stock into a jar or plastic container.