How to Caramelize Onions

Yellow onions caramelize better than any other variety. The sugar content is balanced enough to brown without burning. Sweet onions, red onions, and Vidalias look tempting but they either burn too fast or turn mushy.

For this method you need 3 pounds of yellow onions, which cooks down to about 2 cups of caramelized onions. It's a lot less than you'd think, so don't scale down unless you're cooking a smaller batch deliberately.

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Cut off the top, slice the onion in half pole to pole, and peel off the first outer layer (it's always tough and dry).

Slice each half from root to tip in thin strips, about 1/8 inch thick. This direction of cut matters.

Pole-to-pole strips hold their shape and cook evenly. If you slice crosswise into half-moons, they turn to mush by the end of the cook.

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Use stainless steel, not nonstick. The brown bits (the fond) that stick to stainless are where the flavor develops.

For 3 pounds of onions, use a 12-inch pan with 1/3 cup of olive oil. For 1.5 pounds, a 10-inch pan with 1/4 cup of oil.

Set the heat to medium-high and wait for the oil to shimmer. The oil seems excessive, but you'll pour most of it off at the end. It's not optional - it carries flavor into the onions.

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Tip the sliced onions into the shimmering oil. Add 2 teaspoons of kosher salt (or 1 teaspoon of table salt). Stir once to distribute, then leave the pan alone for about 3 minutes.

The bottom layer needs direct contact with the hot pan to brown, and stirring interrupts that.

Peek at the edges to see how much color they've picked up. When you see golden brown on the bottom, it's time to stir.

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Stir to move the browned bottom onions up and the paler ones down. Let them sit again until the new bottom browns, about 5 more minutes this time.

If the pan looks dry, add another splash of oil. If the brown bits turn black instead of amber, the heat is too high - drop it a notch.

Keep stacking the onions back toward the pan's center after each stir so the edges don't dry out.

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Turn the heat to the lowest setting your burner will go. On an electric stove, move the pan to a smaller, colder burner. The skillet takes a minute or two to cool, so stir more during that transition.

Once the pan cools, the onions can sit 5 to 8 minutes between stirs. This is where the magic happens. The onion strips turn syrupy and jam-like.

20 minutes at low heat gives you tender, sweet onions. 40 minutes gives you deep, almost-burnt-caramel jam.

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Add a splash of balsamic vinegar (about a tablespoon). Stir it in over the low heat for 2 more minutes so it picks up the brown bits. Taste and add salt if needed.

Tilt the pan and push the onions to one side. The excess oil pools at the bottom and you can spoon most of it off.

Save the drained oil for pasta or bread dipping. The onions store in the fridge for about 10 days.

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