What is "salvitxada"

Salvitxada or salsa de calçots is a Catalan sauce originating in Valls, in Tarragona, which is served almost exclusively with calçots at the calçotades, a traditional local barbecue.

It is similar to romesco sauce with the difference that it is thickened with toast rubbed with fresh garlic, moistened with a little vinegar and pulverized.