Croquetas are ubiquitous in Spain, although they most likely originate from the French 'croquettes'. Their beauty lies in the bechamel base which is then mixed with your particular ingredient of choice to give it a characteristic flavor. The possibilities are almost endless - here we have used prawns.
Melt the butter in a medium saucepan and add the flour, stirring continuously. Allow the flour to cook in the butter for a couple of minutes, continuing to stir.
Start adding the cold milk little by little, stirring all the while until you have a thick, smooth sauce. Add the prawns, season well and stir in the tomato paste. Continue to cook for 7 or 8 minutes. The end result should be quite thick. Let the mixture cool completely - it is usually a good idea to leave it overnight.
Take a scant tablespoon of the mixture and form into a croqueta, a 1 1/2 - 2 inch cylinder. Roll the croqueta in the breadcrumbs, then coat in the beaten egg, then roll in the breadcrumbs again. Make sure the breadcrumbs are always dry to ensure an even coating.
Heat the oil for deep-frying in a large, heavy-based pan until the temperature reaches 350ºF or a cube of bread turns golden brown in 20-30 seconds. Fry in batches of no more than 3 or 4 for about 5 minutes until golden brown. Remove with a slatted spoon, drain on kitchen paper and serve immediately.
Tapas are Spain's greatest food invention. "Eat when you drink, drink when you eat" is the philosophy. Spanish men traditionally drink outside the home and rarely alone. They are not meant to be a meal (although a ración is a substantial portion). One tapa per person and a different one with each drink is the idea, then everyone enjoys tasting and sharing.