© Denzil Green
Sweet onions tend to have both a higher sugar level than other onions (6 to 15% sugar level, though there are no legal standards), and a lower sulphur content, which lets the sugar taste come forward.
For an onion to grow sweet, the soil must be low in sulphur. Any sweet variety will acquire a sharper bite if grown in sulphur-rich soil. The fertilizers used must also be low in sulphur. Sweet onions contain about 50% less sulphur than do other onions.
Sweet onions don’t store well because they have thinner skins than other onions, which lets their moisture out, and because they have less sulphur. That’s why good storage onions are always strong-tasting ones: they get their sharp bite from all the sulphur in them.
The shorter storage life means that sweet onions will be moister than other ones, as they haven’t dried out any in long storage. It also means that sweet onions will be more expensive.
Types of sweet onions include Carzalia, Imperial, Maui Sweets, Texas Spring, Vidalia and Walla Walla.
Peeling sweet onions won’t make your eyes well up immediately, the way storage onions do, but if you have to peel and chop enough of them your eyes will eventually feel it.
Eat raw or just cook lightly.