In a large stock pot which can hold at least 10 litres of water, add in all the bones/wings/feet and fill the pot with water until the water is just enough to cover the bones.
Bring it to boil over medium high heat and let it boil for another 5 mins
Remove the pot from the fire and clean the bones/wings/feet under cool running water. Ensure that all residues and dirt are totally clean off. Wash the pot too to ensure that it's clean
The chicken Broth
Add all the cleaned bones/feet/wings back into the pot
Add 8 litres of water and 240 ml of sake
Bring it to boil over medium high heat
Once boiled, reduce the heat to medium low and let it slow boil for another 10 to 12 hours (cover with lid).
Check occasionally.
The water should be reduced by half. Add more water if required.
By 10 to 12 hours, the broth soup be milky in colour, slightly creamy. The longer you boil, the more creamy the broth
Add salt to taste when done.
Let it cool before transferring to a container for chilling in the fridge to set the gelatinized broth - at least 4 to 5 hours (or to freeze in the freezer)
A day before using the broth, put the container of broth in the chiller. (Alternative, just use it straight from the freezer)
Recipe by eckitchensg at http://eckitchensg.com/2016/01/collagen-chicken-broth/