Preheat oven to 180 °C. Place beef bones, onion, carrot and celery into a deep roasting dish. Roast, turning occasionally, for 1 hour and 30 minutes or until browned.
Meanwhile, with kitchen string tie together parsley, thyme and bay leaves.
Transfer bone mixture into a large stockpot over medium-high heat. Fill the pot with water and add the peppercorns and herbs. Bring to the boil. Reduce heat to low. Simmer, uncovered, for 3 hours, skimming the top every 30 minutes.
Remove from the heat and pass the stock through a fine sieve/strainer. Discard solids. Allow to cool, then refrigerate.