It’s a tapa. You take your average potato chips (crisps to the Euro-anglos) and drape some marinated anchovies over them (marinated in oil and vinegar and a little salt). What you get tastes like those Salt & Vinegar flavoured potato chips that I used to love as a kid; but now with all natural ingredients.
See also a variant with Boquerones without chips.
I was up in Madrid and popped out for tapas at a little Asturian place nearby. Ordered all the favorites since I don’t get up there often and we don’t have a place like this anymore down here at the beach. We did… but last season the owner turned the place from a tapas bar into an Indian restaurant - - quite a dramatic change. Now, for tapas, I have to go to the next town over.
Here’s what I had and how they are prepared. Try it at home.
Morcilla: blood sausage, with rice and onions. These were probably sliced and deepfried; at home I just do them in deepish pan.
These are little fried anchovies – Boquerones Fritos or Anchoas Fritas; dusted with a little flour before frying then salting (coarse salt) – they were beheaded and gutted but not deboned; probably soaked in lemon and water for a few hours before cooking.
Pimientos de Padron (from Padron in Galicia) are small hot peppers. An occasional one is super-spicy and surprises you; a sort of Hot-Peppers Roulette. Fried and salted. 
Asparagus, green. Fried and salted. You can see an anchovy spine and hot pepper caps on the edge of the plate there.
This is a tapa. I was travelling up to Madrid a few weeks ago and while waiting at the bus station had a nice glass of red wine. They set out a small plate of homemade garlic and oil marinated anchovies.
No additional charge for the tapa.
These are raw, although slightly pickled, anchovies.
You clean and split the little fishies (fillets – remove the head and tail), debone (don’t worry about any tiny residual bonettes), let them sit in vinegar overnight, then rinse a bit (or don’t rinse, just shake – they’ll be tangier), cover in good olive oil, throw in some sliced garlic. Maybe sprinkle some fresh chopped parsley.
You’re done.
The cautious will put the fillets in a glass dish or between parchment and freeze them for a few hours before doing the vinegar (to –20c, -4f) . There a big panic about raw-fish-borne parasites going around and freezing apparently solves the problem. It must be a recent problem because they’ve been doing boquerones here for the last 1900 years of so without massive parasite issues.
That amounts to a recipe. Try it at home. Start with a kilo of little anchovies. You can maybe do the splitting, cleaning and deboning with your fingers and nail; don’t always need a knife. It will be messy but fun.
