Boquerones en vinagre are a type of appetizer or tapa, meze found in Spain. The central ingredient of the dish is the boquerones, fresh anchovies. The fillets are marinated in vinegar or a mixture of vinegar and olive oil, and seasoned with garlic and parsley.
Fresh anchovy fillets, which initially have a brown colored meat, are cleaned, de-scaled, and submerged in a bath of salt and water for 3 hours and vinegar for 6 hours in a cool place. The fillets slowly turn white as the vinegar reacts with the fish. Once having gone through this process, and the liquid has been drained, they are seasoned with minced or finely sliced garlic, olive oil and parsley. An alternative preparation is to submerge the fillets in a mixture 3:1 of vinegar and olive oil (it can be replaced by sunflower oil), already seasoned with garlic, parsley and salt, for two days. They are served cold with beer, rather than wine, since they already contain vinegar.
The dish is very popular as a tapa in Spain served in restaurants and bars, especially during the hottest summer months. They are garnished with capers or olives and accompanied by potato chips. The prepared fish can be bought commercially, requiring only additional garlic and parsley.
Spanish health laws require the previous freezing of the anchovies when prepared in vinegar, in order to avoid the survival of any Anisakis larvae, even though this parasite is rarely found off Spanish coasts.