[header] How to chop an onion [title] Use a sharp knife. [step] It may seen counterintuitive at first, but a sharp knife is safer than a dull blade. Dull knives not only mash instead of slice into foods, they slip more easily, especially on round, slick foods like onions. 
But dull knives are still plenty sharp enough to cut you. [title] Do it the easiest and safest way if you're not an expert.