Spring onions usually are sold whole and have two distinct parts, the smallish white bulb at the base and the long, fibrous green leaves that make up the top. Depending on the desired size of the chopped pieces, a spring onion can be very easy to chop, because it basically is a long, single strip that can be evenly cut crosswise down the entire length to make small white circles from the bulb and rings or thin strips of the green leaves, if they are being used. Larger spring onions might require special attention, especially for the white bulb, which might need to be treated more like a yellow onion and cut in different directions to get smaller cubes. For a very fine dice, spring onions should be chopped and then the knife should be run back through the resulting pieces until they are as small as needed.
Before chopping spring onions, it is important to wash them to prevent a large amount of dirt and grit from being spread throughout the chopped pieces. The space between the green leaves sometimes holds sand or other material that should be removed under running water. A thin, translucent layer of skin that should be removed might be on the outside of the bulb and the pale area of the green leaves.
For spring onions that are fairly uniform in width from the bulb to the top of the leaves, the first step is to trim off the top of the green leaves so they are evenly aligned and any frayed pieces are removed. Badly wilted leaves also can be cut out. The small knot of roots at the base of the white bulb should be cut away. The remaining part of the spring onion can then be sliced crosswise to the desired thickness. The green leaves might be more difficult to cut than the bulb because they are more fibrous, so a sharp knife should be used for the best results.
If spring onions have particularly large bulbs at their base, then the first step should be to separate the leaves from the bulb. The bulb can first be cut in half and each half sliced into thin pieces against the direction of the rings to make thin strips. The knife can be run carefully through the pile of onion strips to create small cubes. Should the bulb be very large, then the same methods that are used to chop regular sized onions can be used.