Onion is one of those versatile ingredients that you will use in a incredible number of dishes, and yet, it is astounding to see how most people – even people who can consider themselves good cooks – do not know how to chop them properly. Using this technique, you will be able to chop it as thin as you like, and this is the technique that professional chefs use; I learnt it from a pro myself and, after learning it, I suddenly realised how messy and inaccurate I had been until then.
The first thing to consider when doing it is the root. Roots are the base, the foundation, and chopping an onion is no exception.
First thing, trim both ends of the onion, but, on the root side, make sure you only get rid of the outside threads, whilst the inner part of the root should be kept intact, as it will hold the onion together.
Then, cut the onion lengthways, dividing the root in two equal parts, and peel the two halves. Then, with the flat side down and the root end pointing outwards, cut vertically getting as close to the root as you can, but leaving it intact to hold the onion together.
Once done, make horizontal cuts across the vertical cuts holding the onion firmly to allow a clean cut.
I normally chop a whole onion and keep what I don’t use immediately in an airtight container in the fridge. It will last up to a week, and it’s much more convenient than chopping only the quantity you need each time