If you struggle to get an onion into nice small pieces when your recipe demands it, check out these really simple directions on how to chop an onion finely. Also check out the video below demonstrating how it's done.
The first rule of finely chopping an onion is to have a really sharp knife - this way you'll be able to slice through the onion without it falling apart. And when using a sharp knife, always be sure to curl your fingers to avoid a knife injury.
To start with, slice each end of the onion off, peel it then cut it in half. If the root is quiet big, be sure to remove it as the taste of an onion root can be quiet bitter.
You now need to start slicing into each onion half individually. Firstly, make three-four horizontal incisions into each half of the onion, making sure you don't slice all the way through to the other end of the onion. Then make five-six incisions vertically, again making sure you're not cutting all the way up to the end of the onion.
Finally, turn the half onion 90 degrees and start slicing down (which is where having a really sharp knife comes in handy). This will leave you with your finely chopped pieces of onion.