I almost always have onions in my kitchen; usually a few white and red onions, and sometimes shallots. But as much as I really love shallots, I have a tendency to forget about them.
However, thanks to a recent grocery shopping mishap where my fiancé mistakenly bought a dozen shallots instead of a dozen scallions, they're fresh on my mind, and making me consider the possibility of using onions and shallots interchangeably in recipes.
Onions and shallots are both members of the allium family. Shallots have a sweet and mild (although pronounced) flavor, with a hint of garlic, and lack the bite you get with yellow or white onions.
Shallots work especially well in dishes where they're eaten raw, like dressings and salads, and can seamlessly blend into delicate quiches and custards. Yellow and white onions have a more pungent flavor, but they soften and mellow as they cook, eventually taking on a lighter, sweeter flavor.
How to Swap Onions and Shallots
Despite their differences, onions and shallots can be swapped for one another in a recipe. There are a few ground rules, though.
Rule of Thumb for Onion to Shallot Swaps
1 small onion = 3 small shallots
Using Onions When a Recipe Calls for Shallots
If the recipe calls for cooked shallots, go ahead and swap in onions, using the rule of thumb above for quantities. If the recipe calls for raw shallots, move on. Raw onions will be a too-harsh trade for shallots.
Also, since shallots are smaller, with more fine layers than onions, make a point to chop onions into smaller pieces when using them in place of shallots.
Using Shallots When a Recipe Calls for Onions
The flavor is milder, so be aware of that when swapping in shallots for onions.
But swapping shallots for onions is more than a flavor trade-off; the smaller size proves quite convenient. If you're cooking for one, or even for two, or dividing a recipe, using a couple small shallots in place of a portion of onion is easy and economical.
Updated from a post originally published February 2012.