Mint sauce is a green sauce originating in the United Kingdom, made from finely chopped spearmint leaves soaked in vinegar, and a small amount of sugar. Lime juice is sometimes added. The sauce has a watery consistency and is flecked with broken leaves. In British and Irish cuisine it is often served as a condiment for roast lamb, or any other roast meats, or, in some areas, mushy peas.
It is normally bought ready-made, and is easy to find in British food shops. Mint jelly, thicker and sweeter, is an alternative for lamb, also normally bought ready-made.
Similar herb-based green sauces were common throughout Medieval Europe, with the use of mint being more common in French and Italian cuisine of the period than that of the English; however, they became less common and mostly died out as Europe entered the Modern Era.