Romesco refers to the type of chile used to flavor this rich sauce. Romesco chiles can be difficult to find, so we use smoky ancho chiles. Much of the flavor in this sauce hinges on the sweet smoked paprika (pimentón de la Vera dulce); don't substitute regular paprika, which has duller flavor. This batch makes plenty for dressings, to stir into pasta, or to serve with eggs and toast. Freeze leftover sauce in ice-cube trays; transfer to zip-top plastic bags to freeze for up to one month. Thaw in the refrigerator; bring to room temperature to serve.
2 dried ancho chiles
2 small red bell peppers
1/2 cup hazelnuts
1/2 cup blanched almonds, toasted
4 garlic cloves, chopped
1 (1-ounce) slice bread, toasted
1/4 cup red wine vinegar
2 tablespoons tomato paste
4 teaspoons sweet smoked paprika
1/4 teaspoon ground red pepper
2/3 cup extra-virgin olive oil
1/4 cup hot water
1/2 teaspoon salt
How to Make It
Place ancho chiles in a small saucepan. Cover with water; bring to a boil. Remove from heat; cover and let stand 20 minutes. Drain well. Remove stems, seeds, and membranes from chiles; discard. Place chiles in a medium bowl.
Cut bell peppers in half lengthwise; discard seeds and membranes. Place pepper halves, skin sides up, on a foil-lined baking sheet; flatten with hand. Broil 10 minutes or until blackened. Place in a paper bag; fold to close tightly. Let stand for 15 minutes. Peel and cut into 2-inch pieces. Add bell peppers to chiles.
Reduce oven temperature to 350°.
Arrange hazelnuts in a single layer on a baking sheet. Bake at 350° for 8 minutes or until toasted. Turn nuts out onto a towel. Roll up towel; rub off skins. Place hazelnuts in a food processor. Add almonds, garlic, and bread to food processor; process 1 minute or until finely ground. Add chile mixture, vinegar, tomato paste, paprika, and ground red pepper; process 1 minute or until combined. With processor on, slowly pour oil through food chute; process until well blended. Add 1/4 cup hot water and salt; process 10 seconds or until combined.
Note: Store in an airtight container in the refrigerator for up to two weeks.