Place bones in a PADERNO Signature 18/10 Stainless Steel Stock Pot. Cover with water and bring to boil. Drain, discarding water. Return bones to pot; add the cool water, the onion, carrot, celery and leek. Bring to boil; reduce heat and simmer, skimming with a spoon to remove scum from surface occasionally, 2 to 3 hours. Add parsley, thyme, bay leaf and peppercorns during the final 30 minutes cook time.
Strain stock through fine mesh strainer into heatproof bowl; discard bones. Cool stock as rapidly as possible; cover and refrigerate for up to 3 days.
Tip: Stock is an excellent way to utilize the green part of leeks; roughly chop and wash well to remove grit before adding to stock pot.