Romesco is the Catalan sauce made with roasted peppers, almonds, and garlic.
Romesco originated in Catalonia in northeastern Spain. Traditional recipes commonly combine roasted red peppers or ñora peppers with almonds, garlic, olive oil, vinegar, and sometimes toasted bread or tomatoes. The ingredients are ground into a textured sauce with a balance of sweetness, smokiness, acidity, and nuttiness.
Romesco is famously served with calçots, a type of Catalan green onion grilled during seasonal calçotada gatherings. It is also used with fish, shellfish, vegetables, and meats. Recipes vary, and some versions emphasize tomatoes while others rely more heavily on dried peppers.
Romesco is sometimes confused with salbitxada, another Catalan sauce served with calçots. The two are related, but romesco is the more widely recognized name for the pepper-and-nut sauce described here.