Cut out the core of the onion - where the root comes out. This is the section that has the most tear-inducing properties. Soak the onion in water before cutting - water will dilute the sulphuric compounds -or else, freeze the onion before cutting. The sulphuric compound that leads to tears will not react as quickly when it's cold. However, don't freeze it for too long because it can affect taste. 10 minutes should do it. Cut the onion in a well-ventilated room. Give the fumes a chance to escape. Light a candle. A burning flame can burn away the sulphuric fumes. Chew gum or a piece of bread while cutting the onion.