Olive juice is another name for olive brine, the salty liquid olives are cured and packed in. It is prized in bartending for the dirty martini, where a splash replaces or supplements vermouth and imparts a salty, olive-forward flavor, and it plays the same role in cooking as brine: seasoning dressings, marinades, sauces, and braises, or serving as a pickling liquid for vegetables, meat, or seafood. Flavor and saltiness vary with the olives and curing method used, so it should be tasted and added gradually. See 'olive brine' for more detail on how it's made.