Pearl onions don't have quite the sweetness of their larger counterparts, or even of the candy-sweet cipollini or shallots, but they do have a similar bite. What does this mean for cooking them? It means that the best pearl onion recipes are ones that tame the bite while bringing out the natural flavor of the onions without relying on them to provide much sweetness.
For me that means one of two methods: glazed or creamed. Both methods start out the same: by peeling pearl onions.
The easiest way to peel pearl onions is to not bother doing it at all and just pick 'em up peeled and frozen. In our blind taste test, we found that tasters were pretty evenly split on fresh vs. frozen onions. If you've had them frozen in the past and enjoyed them, there's no reason to switch.
But if you do want to start with fresh ones (they tend to have a slightly firmer texture and milder flavor when cooked), you can peel them by first cutting off the tops and bottoms with a paring knife and scoring one cut side with a small X in order to help you peel off the skin later on. After that, it's a quick dunk in a hot pot of boiling water just to loosen the outer layers. About one minute will do you. After a shower under the cold tap, they should be easy to peel with your fingers. (Here's a short video that demonstrates the process.)
From here, we branch out in two directions. Glazing is one of the simplest, all-in-one-pan methods for cooking vegetables. You start by covering the vegetables with water (or unsalted stock if you prefer) and adding some butter, salt, and sugar. Then all you do is bring it to a boil over high heat and let that water simmer away.
As the water simmers, the vegetables soften, flavoring the liquid, which eventually reduces and emulsifies with the butter, forming a glossy, flavorful glaze that coats the tender vegetables. The whole process takes about 20 minutes. The key here is to stop cooking just before the sauce becomes very tight. Take it too far and you'll end up evaporating too much moisture, causing the butter to break into a greasy pool. If this happens, just stir in a bit of tap water or stock and shake the pan vigorously to bring it all back together.
Creamed onions, on the other hand, are all about slow, slow cooking to produce a rich, mellow flavor. Some folks like to add a flour and butter roux to thicken and stabilize their creamed onions. As with other avenues in life, I prefer my creamed onions au naturel, with nothing but heavy cream to coat them with (and ok, a bay leaf to flavor that cream).
Whether you cream or glaze your onions, chopped parsley is a perfect partner.
About the author: J. Kenji Lopez-Alt is the Chief Creative Officer of Serious Eats where he likes to explore the science of home cooking in his weekly column The Food Lab. You can follow him at @thefoodlab on Twitter, or at The Food Lab on Facebook.