Caramelise

To caramelise is to heat sugar, or food that contains it, until it turns brown and develops a deeper, nutty, slightly bitter sweetness. American recipes spell it caramelize.

In the strict sense it means sugar on its own: melted in a dry pan or dissolved in water and boiled until amber, for caramel sauce, crème caramel or a brûlée top. Swirl the pan rather than stirring, and take it off the heat a shade before it looks right, because it keeps darkening.

Recipes also use the word loosely for slow-browned vegetables, above all onions. Caramelised onions take far longer than most recipes admit: sliced onions in butter or oil over a low to medium heat, stirred now and then, usually need well over half an hour to turn soft, sticky and deep brown. Turning up the heat burns the edges before the middles soften.

Roasting caramelises too, which is why roast carrots, parsnips and squash taste sweeter than boiled ones.