Maui onions are a variety of sweet onion which are widely cultivated on the Hawaiian island of Maui, although they can be grown in other regions as well. Like other sweet onions, Maui onions lack the sulfur which causes the strong odor and sharp taste associated with onions. The State of Hawaii has invested a great of money in marketing their famous onion variety, putting it on par with Vidalia onions from Georgia, another sweet onion variety. Many markets carry Maui onions in season, along with other sweet varieties, and if you live in a temperate zone, you may be able to grow some yourself.
Hawaiian farmers claim that a true Maui onion must be grown on Maui, because this distinct onion cultivar flourishes best in the rich volcanic soil of Mount Haleakala, the dormant volcano which dominates the landscape of Maui. The volcano's rich, distinctive red soil may well be responsible for the distinctive sweet flavor of the Maui onion, although the warm weather on the island probably has something to do with it as well.
In addition to being very sweet, the Maui onion has a high water content, making it quite juicy. There are a number of ways to use these flavorful onions. Some people enjoy eating them raw out of hand, and they are also good when sliced thinly on salads, sandwiches, and other dishes. The onions can also be cooked, bringing out even more of the naturally sweet flavor; they are great grilled, and they can also be marinated with other vegetables for kebabs, included in stuffings, or used to make distinctive sauces.
Typically, Maui onions are among the first of the sweet onion varieties to be available in the spring, because the growing season on Maui starts early; start looking for them at around April. They have a rich golden yellow color and they typically grow in a slightly flattened shape; when seeking out onions in the store, check for soft spots, which can indicate that the Maui onion has gone bad.
Onions are tricky to grow. The Maui onion plants require long, warm days to set bulbs, and they are very responsive to impurities in the soil; if you have sulfurous soil, for example, the bulbs will pick it up as they grow. If you want to grow Maui onions, you can order seeds from Hawaiian farms or through your local garden store. Plant the onions in well fertilized soil after the last chance of frost, and keep the soil moist, but not wet, as the onions grow. They will start to set bulbs in warmer weather, and as the weather gets hot, the plants will begin to go dormant. Taper off your watering as the plants go dormant, and harvest the onions when their stalks have withered.