Cooking in aluminium foil in the pan

Hi everybody! I saw on a bento book a method for cooking small amounts of food at the same time: they put an aluminium foil below an ingredient in the 18 cm non-stick pan, so for example they are able to cook chicken in a half of the pan (on a piece of aluminium foil), and some vegetables in the other half, on the pan or on another piece of aluminium foil. Then if you want to cook some other food you just have to use a new aluminium foil and the pan is already clean! I thought I found the japanese secret for cooking small amounts of many dishes at once,
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