Updated 1 August 2026 · Written by Daniel Wright
To caramelize onions, cook thinly sliced onions in butter or oil over low to medium heat, stirring often, for 30 to 45 minutes until they turn soft, golden brown and sweet. Add a pinch of salt to draw out moisture, and deglaze the pan with a splash of water if they stick. The key is low heat and patience.
Cook thinly sliced onions in fat over low-medium heat, stirring, for 30 to 45 minutes until deep golden and sweet.
The Method
- Thinly and evenly slice the onions so they cook at the same rate.
- Cook in butter or oil over low to medium heat, not high, which burns rather than caramelizes.
- Stir often and add a pinch of salt to release moisture.
- Deglaze with a splash of water when browned bits stick, and keep going for 30 to 45 minutes.
Why Low and Slow
Caramelizing slowly breaks down the onions’ natural sugars for a deep, sweet, jammy flavor. Rushing on high heat just chars them. If cutting onions makes you tear up, see why onions make you cry. A heavy pan or Dutch oven spreads the heat evenly.
Frequently Asked Questions
How long does it take to caramelize onions?
About 30 to 45 minutes over low to medium heat. Anything faster is browning, not true caramelizing, which needs time for the sugars to develop.
Why won’t my onions caramelize?
The heat is likely too high, which burns them, or the pan is crowded. Use low to medium heat, stir often, and give them time.
