While once it seemed as though the only onion options were the generic sounding yellow, white and red, each variety of onion in the market is now labeled clearly - and there are a lot of them, in addition to those three standards. But what is the difference between them? The primary difference is sweetness, with some onions, known as sweet onions, lacking the sulfuric bite that most associate with an onion.

Sweet onions usually are available in summer and have a higher water content than so-called "storage onions", which contributes to their mild flavor. It also means that they have a somewhat shorter shelf life and are more delicate, prone to bruising, than their less-sweet counterparts. They can be used interchangeably with regular onions in cooking, since they will handle almost identically, but they will impart slightly different flavors to the finished dish. Many people prefer sweet onions in dishes that call for raw onions, such as salads, or for use on burgers and hot dogs.

There are many types of sweet onions, grown all over the country, and each has a slightly different flavor profile. Unsurprisingly, there is a lot of debate over which sweet onions are the best tasting, and each region tends to favor their own. Vidalia is the most widely available sweet onion, originating in Georgia. California grows a variety known as the Sweet Imperial. Other types include Walla Walla, Texas Sweet, Carzalia Sweet, Oso Sweet, Arizona, Granex, and Maui (my personal favorite). All have a crisp texture and light flavor. Spanish onions are halfway between sweet and not sweet, so they make a good substitute when sweet are not available.

When choosing sweet onions, opt for ones that are heavy for their size and to not look bruised or wrinkly, which is an indication of age. Sweet onions can be stored for 4-6 weeks in a cool dry place, which is not quite as long as "storage" onions can be kept. Once sliced, the onion should be wrapped, refrigerated and used within a few days.

As already noted, sweet onions make a great addition to all kinds of salads, but here are a few more recipes to get your cooking:

• Chickpea & Tomato Salad
• Sweet Onion & Cucumber Salad
• Poppy Seed Sweet Onion Risotto
• Sweet Onion Soup with Goat Cheese Toasts
• Rustic Sweet Onion Pie
• Tomato and Sweet Onion Focaccia