Muddling is the technique of gently crushing fresh herbs, fruit, or spices with a blunt tool called a muddler to release their aromatic oils and flavor into a drink or dish, without pureeing or juicing them.
The muddler is pressed and twisted against the ingredients at the bottom of a glass or bowl; light pressure for about 10-15 seconds is usually enough to release aroma without crushing woody stems or bitter pith, which can turn the drink bitter or astringent. The technique is closely associated with cocktails such as the mint julep and the mojito, where it is used on mint leaves, lime, and sugar, but it is also used to build flavor bases for salsa, guacamole, and marinades.
Muddling differs from juicing or blending in that it releases essential oils and juice from the surface and cell walls of an ingredient while leaving it mostly intact, giving a gentler, less bitter result than fully pulverizing the same ingredient.