White chicken stock

• 6 chicken carcasses
• 4 large white onions, cut in 6
• 1 head celery

In a pot, place chicken carcasses and cover with cold water, bring to the boil and skim. Mix. Turn heat to low and skim all fats and froth. Add all ingredients. Keep the stock on low heat and skim continuously for 3 hours minimum. Pass through a colander into a bowl. Press down on solids to extract maximum liquid. Pass liquid through a chinois and cool down.