Boquerones are unsalted anchovies (a fish) cured in vinegar. " Anchovies" are the same fish preserved in salt.
Boquerones are tender, white and juicy, and have a milder, more delicate flavour than processed anchovies usually do, missing their fishy or salty taste.
They are not cooked before being cured.
Boquerones are packed in olive oil and vinegar, along with garlic and parsley, and must be kept refrigerated.
In making Boquerones at home, the fish are cleaned then filleted. The heads and tails are cut off, the fish slit open, the innards removed, the central bone lifted out, and the fish carcass rinsed with water. The fish are then layered in a shallow dish, and soaked for a few hours in either white wine vinegar, or water and vinegar. Some people will sprinkle with some salt first to remove the blood. The acidity in the vinegar both softens the remaining bones and whitens them. Some people will drain the fish once during the soaking process and replenish with fresh liquid; others will put them in the fridge to soak overnight.
The soaking liquid is then drained and discarded, and the fillets are rinsed with water, then completely covered with olive oil mixed with some sliced garlic and chopped fresh parsley to taste. The fish mixture needs a while to marinate in the fridge before using, at least two weeks.
Commercial methods will vary. One way is to first flatten the fillets with heavy weights for a while, then they are rinsed with brine, and put in machines which remove excess water by centrifugal force. Finally they are packed in oil and white wine vinegar.
Boquerones are often served fried as "tapas" or as a starter.
To fry Boquerones, cut them in half through the middle, dip in milk, dredge in seasoned flour, then fry until crispy in a small amount of hot oil.
In the Basque area of Spain called "anchoas"; in Asturias called "hombrinos". Singluar is boquerón.