Mint sauce
Mint sauce is a green sauce popular in the United Kingdom, made from finely chopped spearmint leaves soaked in vinegar, and a small amount of sugar. It is a traditional accompaniment to roast lamb. There are many different species of mint, but the one used most widely in Western cooking is spearmint . It is native to the Mediterranean area but is found in many other parts of Europe and in North America. The Oxford Companion to Food calls it "[v]ery widely cultivated and used ... 'the mint' of cooks, the one commonly used for mint sauce and for flavouring new potatoes and peas, in Arab mint tea, etc." The Ancient Roman naturalist Pliny the Elder wrote that mint "stirs up the mind to a greedy taste in meat". The later Roman writer Apicius gave a recipe for mint sauce which he said complemented the flavours of roast lamb (or suckling kid). By the Middle Ages mint was commonly found in European medicinal and kitchen gardens, as well as growing wild.
Source: Wikipedia