Calcots (or calçots) are a type of scallion in the onion family. As a result, in the UK they're commonly known as calcot onions
Calcots are a type of onion and Valls is very much a calcot town. They were invented - in so far as an onion can be invented - in the town in 1898 by a farmer called Xat de Bernaiges, who dug up his white onions five months after he had sown them and then replanted them. As the shoots lengthened, he built a protective stocking of earth around them. The result was a long, sweet-tasting onion
The way to eat a calcot is to grip firmly on the inner stalks at the top end with one hand and pull firmly but gently down on the outer stalks towards the root with the other. Done successfully, the outer, charred, layers come cleanly away to reveal the sweet, soft, inner onion. The freshly de-sheathed calcot is then dipped in the sauce and hurriedly consumed, sword-swallower style. A good sauce is that one that clings, with the vinegar and garlic adding bite and the nuts a bit of texture.