How to chop an onion > Task 1]]> First, cut the top off the onion. Then halve the onion. Place the flat side down. Slice the onion from the side using a finger to guide the knife. Don't cut all the way through, only score it. Hold the partially sliced onion together and start to slice through. At the end push the onion away, then chop the last bits. Throw away the stalk.