Why It Works
- Caramelizing the onions slowly in butter until they're rich golden-brown (but not so dark as to taste bitter) produces the sweetest, most flavorful results.
- There are no tricks here for faster results; we've tried them and are not impressed.
There are plenty of tricks and hacks out there for "quick caramelized onions," but the best caramelized onions cook low and slow until they're sweet and soft enough to practically melt in your mouth. These thinly sliced onions cook for one to two hours, at which point they're perfect for spreading on toast, dressing up a burger, folding into a sandwich, or throwing on top of a pizza. They're also the perfect base for the best French onion soup.
- 6 tablespoons (90g) unsalted butter
- 3 pounds (1.4kg) yellow or mixed onions, sliced 1/8 inch thick (see note)
- Kosher salt and freshly ground black pepper
In a large stainless steel saucepan, or in 2 large stainless steel or cast iron skillets, melt butter over medium-high heat until foaming. Add onions and cook, stirring occasionally, until softened, about 8 minutes. Lower heat to medium-low and cook, stirring frequently, until onions are very sweet and a rich golden-brown color, 1 to 2 hours. If browned onion juices on bottom of pot threaten to burn, add 1 tablespoon (15ml) water, scrape up browned bits, and continue cooking; add water whenever needed to prevent burning. Season with salt and pepper.
Large stainless steel sauté pan or cast iron skillet
Yellow onions are your best all-purpose bet, but a mix of yellow, sweet (e.g., Vidalia), and red onions, as well as shallots, produces an even more complex flavor.
Make-Ahead and Storage
The onions can be refrigerated in a sealed container for up to 1 week. Rewarm before serving.