Boiling
The best way to peel pearl onions is to blanch them in boiling water. It’s quick and easy, and the onions emerge intact and perfectly smooth, ready to use in whatever dish you had in mind.
Bring a large pan of water to the boil, then add the onions and boil for 2 minutes. You should see the skins start to peel away as they boil.
Remove the onions and place in an ice bath to stop them from cooking.
Remove the onions from the ice bath and place them on some paper towels to drain.
You should now be able to rub the skin away easily with your fingers. For the smallest onions, you can squeeze them at one end and they will pop right out of their skins.
Microwave
If you need pearl onions in a hurry, the quickest way to peel them is simply to place them in the microwave for 20 to 30 seconds. As with blanching, this should loosen their skins so they can easily be removed. It will also partly cook the onions, however, and you may find that they have deflated a little in the microwave, so avoid this method if appearance is important.
How to cook pearl onions