Caramelised onions are deeply softened and browned throughout, with a concentrated sweet and savoury flavour. A few dark edges on otherwise crisp onion are a different result. Give the onions time to lose moisture before expecting sustained browning.
Step by step
Slice and choose a roomy pan
Slice the onions evenly and separate the layers. Choose a wide, heavy pan with enough room to stir. A deep mound will take longer to release its moisture.
Soften in a little fat
Warm the recipe’s oil or butter over moderate heat and add the onions. Stir to coat, then cook until they begin to collapse. Adjust the heat so the pan sizzles gently without rapidly burning the edges.
Continue cooking and stir more often
As water evaporates, the onions begin to colour. Stir from the bottom, bringing darker pieces into the rest. Lower the heat as they become drier; expect a gradual change from pale to golden to a deeper brown.
Release brown deposits when needed
If brown residue builds on the pan, add a small splash of water and scrape it into the onions. Let that water cook away before repeating. Stop when the onions are soft, evenly brown and suited to the dish.
Black flecks or a wet pan
Dark brown deposits can add flavour; blackened residue tastes burnt. Do not scrape black residue into the onions. If they remain watery, give moisture time to evaporate instead of immediately increasing the heat. A fixed short time cannot account for every onion quantity, pan and burner.
