History
Onions are originally from central Asia and have been domesticated for over 5,000 years. They are probably the most common ingredient in cooking in almost all types of cuisines. In fact, it often stands out and is noticeable when you find an recipe that omits them.
Swim goggles have been 100% effective for me at stopping crying when cutting onions. It may look a little goofy, but it’s a lot better than looking like you just finished watching Homeward Bound.
I prefer cutting an onion by first pulling off the hairy roots but not peeling it yet. Then cutting it in half across its equator, then each half in half again right down the middle, even if that’s directly through the end. Then I put it on its side so that the end is against the cutting board and cut it off as thinly as I can while still getting all of it. Then I peel off the dry skin since it’s much more loose now and comes off a lot more easily. When I’m cutting the root end, I cut a deep V around the extra thick part to remove it. With the onion still on its back as it was when you cut the end off, slice straight down all the way through parallel to the cut you made across the equator. Make these cuts about 1/4 – 1/2 inch apart, or however large you like your onion. Then, using the side of the knife, slide the blade under the onion and tip it so the other flat side is now facing down. Now, slice from one side to the other, about the same thickness you did the first cuts. You can use parallel cuts or rotate the knife around the middle, however you prefer them.
Using a sharp knife is key, both for ease and safety.
I prefer a coarser cut for more rustic dishes such as soup, but a much finer chop if not a dice for onion that will be in something such as a cream based sauce.
Types
In general, onions are quite interchangeable, so don’t worry if the best type isn’t available at the grocery store, any alternative is fine.
White
White onions have a cleaner, lighter flavor. They are best used raw, such as on traditional style tacos, or with fast, hot cooking such as in stir fry or fajita veggies.
Yellow
Yellow Onions are strong and sweeten when cooked. They are a great all purpose onion. If you’re not sure which type to use, it’s a safe option.
Sweet/Vidalia
Sweet onions are mellow and higher in sugar. They are great raw on salads. They’re also commonly used in cream based sauces.
Red
Red onions are mild, sweet, and vibrant. They are best used raw. I also like to use them when I’m making something very colorful, such as a salad or a Mexican dish with a mix of different colored peppers.
Shallots
Shallots are a blend of delicate, complex flavor. These are more common in cream based sauces.
Green Onion/Scallions
Green onions are much milder in flavor than the other types. They are usually used raw in dishes such as salad or as a garnish. They are also used in Asian style soups. They can generally be used as a much milder substitute for other types, although cooking time is typically much shorter.