Sweating (cooking)

Sweating in cooking is the gentle heating of vegetables in a little oil or butter, with frequent stirring and turning to ensure that any emitted liquid will evaporate. Sweating usually results in tender, sometimes translucent, pieces. Sweating is often a preliminary to further cooking in liquid; onions, in particular, are often sweated before including in a stew. This differs from sautéing in that sweating is done over a much lower heat, sometimes with salt added to help draw moisture away, and making sure that little or no browning takes place.

close-up view of sweated onions

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Wikipedia