What does it mean to ‘fold’ in cooking?

The process of 'folding' in cooking refers to the method of gently combining a light ingredient into a heavier mixture. This technique is commonly used when incorporating whipped cream, egg whites, or other light mixtures into a batter or dough. The goal is to preserve the airiness and volume of the lighter ingredient, which is crucial for achieving a light and fluffy texture in the final dish.

Folding involves using a spatula or a similar tool to lift the lighter mixture from the bottom of the bowl and gently turn it over the heavier mixture, rotating the bowl as you go. This motion helps blend the ingredients without deflating the air that has been incorporated, which could happen if the mixtures were vigorously stirred or beaten. This technique is particularly important in baking recipes for soufflés or mousses, where maintaining airiness is key to the desired outcome.

The other options describe different cooking techniques that do not align with the purpose or method of folding. Mixing vigorously would result in a loss of air, while slicing ingredients is a cutting method, and leaving ingredients in separate layers does not involve any combining at all.