I'm a pro chef – here's why this tiny knife sharpener belongs in the kitchen of any serious cook

This sharpener is easy to use and does the job well enough to please a professional chef The seven best air fryers, tried and tested in a food lab Sign up for the Filter US newsletter, your weekly guide to buying fewer, better things In every cooking class that I teach, knife sharpening is the first lesson my students learn.

Dull knives are inefficient and dangerous – a dull blade can slide right off the curvature of an onion into the flesh of the hand holding it. At the Drexel Food Lab , where I’m a certified research chef and culinary educator, we use a Tormek T2 Pro Kitchen Knife Sharpener , donated by the…