Add hot water, salt, brown sugar, garlic, bay leaf and peppercorns in to the pan and cover tightly. Bake at 150ºC for 2-3 hours until the meat is so tender that the bones can be lifted away using tongs.
Leave to stand until cool enough to handle.
Strain stock into the bowl and skim away the fat.
With the skin side down, use tongs to lift the bones out of the head meat. Discard any dark or discoloured meat, eye and any cartilage. If discarding fat, take care not to throw out any light-coloured meat.
Cut the meat into chunks.
Taste stock. If too salty, dilute with water to get 2 cups of liquid.
Soften gelatine in ¼ cup of cold water, then mix with the stock. Add chopped onion, sage and chunks of meat. Bring to the boil and simmer for 2 minutes. Pour into loaf tins or bowls and leave to set.