If you own an electric chopper, cut and remove the outer skin of the onion and use the chopper. You might also have to cut the onions in halves before placing them in the chopper. Read the electric chopper’s instructions manual to get the best results.
Cut and peel the papery skin of the onion. Halve the onion and start cutting the onion into slices lengthwise. Once the slices are made lengthwise, turn it 90 degrees and start slicing widthwise to get a diced onion. If you want to mince the onion, make slices thinner or keep chopping when the onion is diced.
The rough and fine chopping is easy and can be done by amateurs who don’t chop onions very often. Slice the onion into two halves and cut the hairy edges. Remove the outer skin of the onion and lay both pieces flat on the chopping board. Start slicing them and don’t worry about the size of the slices. When the onion is sliced, start chopping by cutting random smaller pieces. Keep chopping until the pieces are of the desired size or minced.
Slicer dicers have sharp blades that can dice your onions into the attached box instantly. Cut the top and bottom hairy part of the onion and get rid of its outer layer. Open the slicer dicer and place the onion inside it. Close the lid and push the onion through the blades to get them evenly diced in the box.