Put all of the ingredients except the chicken into a 7 litre (245 fl oz) stockpot with a tight-fitting lid, bring to the boil and simmer on high for 10 minutes without the lid. Strain the liquid into another stockpot, discarding the solids. Bring the liquid back to a full boil then put the whole chicken—breast side down—into the pot. Immediately put the lid on the pot and turn off the heat. Remove from the heat and allow to stand for exactly 1 hour. Remove the chicken from the liquid and place on a draining tray. Refrigerate for at least 45 minutes or until required.
Note: with this cooking method the chicken flesh will appear slightly pink, but it will be cooked through. The flesh should give between your fingers: if it doesn’t, you will need to cook it a little longer.