Preheat oven to 375 degrees F. Place bones in a large roasting pan. Roast until golden, 40 minutes. Stud each onion with 3 cloves. Place the roasted bones in a large stock pot with water. Bring to a boil, skim foam and reduce heat to low. Add carrots, celery, leek, garlic, parsley, thyme and bay leaf and simmer, uncovered, for 5 hours.Advertisement
Strain through a fine sieve. Skim fat, if using immediately, or refrigerate overnight and remove solidified fat.
To make ahead: Cover and refrigerate for up to 2 days or freeze for up to 6 months.
Nutrition Note: After straining and skimming, broth has negligible calories and nutrients.