Preheat the oven to 400°F.

Rub a little olive oil over the stew meat pieces, carrots, and onions. Place stock bones, stew meat or beef scraps, carrots and onions in a large, shallow roasting pan. Roast in oven for about 45 minutes, turning the bones and meat pieces half-way through the cooking, until nicely browned.

When the bones and meat are nicely browned, remove them and the vegetables and place them in a large (12 to 16 quart) stock pot.

Place the roasting pan on the stovetop on low heat. Pour ½ cup to 1 cup of hot water over the pan, and use a metal spatula to scrape up all of the browned bits stuck to the bottom of the pan. Pour the browned bits and water into the stockpot.

Add celery tops, garlic, parsley, bay leaves, and peppercorns to the stock pot. Fill the stock pot with cold water, to 1 to 2 inches over the top of the bones. Put the heat on high and bring the pot to a low simmer. Reduce the heat to low.

Cover the pot loosely and let simmer low and slow for 3 to 6 hours. Do not stir the stock while cooking.

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.

At the end of cooking time, use a slotted spoon or spider ladle to gently remove the bones, chunks of meat, and vegetables from the pot and discard.

Line another large pot (8-quart) with a fine mesh sieve, covered with a couple layers of cheesecloth if you have it. Pour the stock through the sieve to strain it of remaining solids.

Let cool to room temperature then chill in the refrigerator. Once the stock has chilled, any fat remaining will have risen to the top and solidified.