Blanch the bones by bringing them to a boil in enough water to cover, then simmer for 5 minutes. Drain and rinse.
Put the bones and vegetables in a stockpot. Add the bouquet garni, peppercorns, garlic and water. Bring slowly to a boil, skimming often. Simmer for 4-5 hours, skimming occasionally.
Strain and taste the stock. If the flavor is not strong