Here's the stuff that we know about Spring Onion...
Also known as scallions or green onions, spring onions are in fact very young onions, harvested before the bulb has had a chance to swell. Both the long, slender green tops and the small white bulb are edible, and are good either raw or cooked. They have a similar flavour to onions, but are much milder.
How do I get Spring Onion ready to use?
Wash, then trim off the root as well as any ragged ends at the top. Slice the bulb into rounds. Cut the green tops across (kitchen scissors are good for this) or lengthways with a knife, then lengthways again, according to what shape you'd like. If you want to make the tops into a garnish, cut into slim lengths, as above, then stand in ice cold water for 30 minutes.
What about keeping Spring Onion?
In a perforated bag in the fridge. Spring onions don't last as long as onions, so use within four or five days.