The Catalan sauce traditionally made with roasted red peppers, tomatoes, garlic, nuts, and olive oil is romesco.
Romesco originated in the fishing district of Serrallo in Tarragona, Catalonia. Its foundation usually combines roasted tomatoes and garlic with almonds, hazelnuts, or pine nuts, oil, and dried nyora peppers, a small red pepper associated with the region. Bread or flour may be added to thicken the mixture, while vinegar provides acidity.
Recipes vary considerably, so there is no single universally fixed ingredient list. Romesco is often served with seafood, grilled meats, vegetables, and poultry. It is frequently confused with salvitxada, a related Catalan sauce traditionally served with calçots, or grilled spring onions; the two sauces overlap but are not identical.