Fully grown white onion bulbs are planted in the fall, let grow for a few months, then gathered and stored. They are then replanted the next fall. They sit dormant in the ground during that subsequent winter, then grow the following spring from late January to the start of March. As they regrow, the stalks are covered with earth to a certain point to keep them white. When harvested, the stalks and bulbs are both harvested. They look like fat green onions, except that the white part is much longer.
Calçot festivals are held at which the entire harvested onion plant is cooked outside on wire racks over coals made by burning branches pruned from grapevines. Before cooking, the stalks are shortened a bit, and the roots are trimmed off the bulb. They are then cooked till charred outside, tender inside, then wrapped in paper to sweat a bit after cooking. This both cooks them a bit more with their residual heat and loosens the charred skins. The paper (frequently just newspaper) also keeps them hot until they are purchased to be taken to a table for eating.
Then they are put on clay roof tiles along with a dipping sauce, which is usually “Romescu” sauce, or a sauce called “Salsa de los Calçots.”
You hold the onion by the stalks, and with your other hand, slide the burnt outer layer off. The charred outside skin is discarded, and the white bulb part at the bottom dipped in the sauce and eaten. The cooked bulbs end up sweet, creamy, tender and smoky.
The festival has been held in Valls since 1982. More is actually eaten than the onions: a meal is made of it, including butifarra (blood sausage.)
Since 1995, there have been quality controls on the production methods.
Romescu, or romesco, sauce is a red sauce made from red peppers, ground almonds, olive oil, and garlic.
Salsa de los Calçots</h2>]
Every family has its own secret version which includes hazelnuts, tomatoes and vinegar.
Baby leeks, green onions.
Calçots either get their name from the Spanish word for stocking, calça — or comes from a word meaning to hide, as the stalk is hidden in the earth.
A calçotada (plural: calçotades) is a meal celebrating, and featuring, the onions.
Calçot is pronounced “kalsot.”
Zalewska, Anna. Feting the humble onion in Catalonia. Toronto, Canada: The Globe and Mail. 14 March 2009.