Insulation. Heat capacity. Temperature. And why double-boiling is worth the toiling.
Chinese soups are often double-boiled. Double-boiling is a cooking technique where a large pot of water is put to boil. A smaller pot of water containing the soup’s ingredients is then placed — often suspended — in the water in the larger pot (see diagram).
The large pot’s water insulates the smaller pot from the direct heat of the fire. Water has a large heat capacity, which is the amount of heat needed to raise the temperature by 1 degree. Hence the heat from the fire is transferred gradually to the smaller pot of soup.
The soup is thus cooked slowly and gently. There is little risk of the soup burning. The nutrients and flavors in the ingredients are also fully extracted.
It is why double-boiling is the preferred method for cooking expensive ingredients such as medicinal herbs. These can be cooked on their own; they are also often used as ingredients in soups. Double-boiling needs a little more toiling at the fire, but those who have done it swear that the yumminess and nutritional benefits are worth all the trouble.
You might have noticed that the photo above used the winter melon itself as the smaller pot. You can also use a young coconut (as you can see in this recipe from What to Cook Today). They work because they are waterproof. They are also friendly to the environment — they are found in nature and there is no need to wash them after. Plus it’s a fun experience to eat out of them!
What other foods and recipes use this double-boiling technique? Share them with me!
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photos: in order – depositphotos/asimojet; marilyna; heinteh