Choosing onions

Onions are cheap and keep well, which means that most grocery stores offer a surprisingly wide variety. Even your regular old Safeway will have at least four varieties of onion on hand.

The first question you should ask is, what is the onion for? Will you be cooking with it, or eating it raw? And if it's to be raw, what kind of flavor do you want - a good sharp bite, or a mild and softer crunch?

Yellow Onions
For cooking, the regular old workhorse yellow onion is almost always what you will want.

White Onions
If you are cooking Mexican food, then a white onion may be the way to go. White onions are more harsh, but they have a brighter flavor which makes them the traditional choice for Mexican cuisine. White onions are also good if you're making your own salsa fresca (which you totally should because it is delicious).

Note: Don't just blindly choose your onions. Look them over first. I find that the white onions are typically in better shape than the yellows. If the yellow selection is unusually poor, you're better off with a white onion rather than a bruised or moldy yellow.

Red Onions
Red onions are great in salads and on sandwiches. They have a nice crisp crunch, a medium-strong flavor and add a bit of color to boot.

Sweet Onions
Sweet onions are also good in sandwiches, burgers, and (chopped fine) as a hot dog topping. Sweet onions are NOT good in cooked dishes. Their mild flavor often gets lost in the rest of the dish, and their tender texture quickly turns mushy and unappetizing.

Shallots
Shallots are an interesting "edge case." Because of their more pungent, somewhat garlicky taste, you will probably NOT want to use them raw. They are more difficult to peel and chop, so I wouldn't use them if the dish calls for a lot of onion. And they tend to melt into whatever you're cooking, so if the crunchy texture of onion is important, then don't use shallots. But this interesting onion cousin provides a richer flavor which is particularly good in French cuisine.

Image courtesy Flickr/Svadifari