How to Properly Caramelize Onions
Most people give up when the onions turn golden after ten minutes. True caramelization requires at least forty-five minutes of steady, gentle heat to reach the point where the onions lose their bite and gain a complex, concentrated sweetness.
The heavy bottom is your best friend.
Thin pans create hot spots that burn the onions before they can caramelize. Use a heavy cast iron or stainless steel pan to distribute heat evenly throughout the long process.
- Heavy-bottomed wide skillet
- Wooden spatula
- Chef's knife
What goes in.
- 3 largeyellow onions, peeled and sliced pole-to-pole into 1/4-inch strips
- 2 tbspunsalted butter
- 1 tbspneutral oil
- 1/2 tspkosher salt
Managing the Fond
When a dark brown crust forms on the bottom of the pan, add a splash of water or broth and scrape it up immediately. This incorporates the sugars back into the onions, deepening their color and flavor.
The method.
Heat the fat
Place your skillet over medium heat. Add the butter and oil. Once the butter foams and settles, add the onions.
Sweat the onions
Toss the onions to coat them in fat. Cook for 5 minutes until they begin to wilt and turn translucent. Stir in the salt.
Control the heat
Lower the heat to medium-low. This is the stage where you leave them alone for 10-minute intervals before stirring. The onions will shrink significantly.
Monitor the transformation
After 30 minutes, they will be tan. After 45-50 minutes, they should reach a deep, rich brown. If they look dry or are sticking aggressively to the pan, add a tablespoon of water.
Finish
When the onions are uniform in color and have the consistency of marmalade, remove them from the heat.
Other turns to take.
Balsamic Finish
Add a teaspoon of balsamic vinegar in the final minute of cooking to brighten the deep sugars.
Herbed
Toss in a sprig of fresh thyme halfway through the cooking process for an aromatic finish.
When it doesn't go to plan.
Do not crowd the pan; if the onions are piled too high, they will steam rather than brown.
If the onions begin to blacken, your heat is too high—immediately pull the pan off the burner and add a splash of water to lower the temperature.
Store cooled caramelized onions in a glass jar in the refrigerator for up to five days.
The ones that keep coming up.
Can I speed up the process with high heat?
No. High heat will char the exterior and make them bitter before the sugars inside have time to break down.
Should I cover the pan?
Keep the pan uncovered. A lid traps steam and keeps the onions wet, which prevents the browning necessary for caramelization.
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