Picada is a sauce – sort of. You might eat it without realising it since it is generally stirred into stews, braises and soups just before they are served. It is seldom served separately like rouille, mayonnaise or aïoli. The basis is nuts. It is pretty much peculiar to Catalonia and Valencia. Elsewhere in Spain picada means minced meat: there’s a small chain of burger and grill restaurants in Madrid called La Vaca Picada, The Minced Cow.