What is the meaning of idiom onion skin?

Answer 1

paanu?

Answer 2

If something is like an onion, it is a layered problem. Peeling the onion would be addressing the problems one at a time, and possibly harder and harder - just like an onion has more odor the more you peel.

Onion skin can also be a reference to a type of paper, often the type used for making carbon copies. The paper is thin and rustles as you touch it, and feels a bit like the outer onion peel.