Spanish Red Pepper Romesco Sauce

Position oven rack 4 to 5 inches from heat source; preheat broiler. Line a rimmed baking sheet with foil.

If using chiles, put in a small saucepan and cover with water. Bring to a boil, then remove from heat. Weight the chiles down with a small plate and let stand for 20 minutes.

Meanwhile, place bell peppers on the prepared pan and broil, turning occasionally, until blackened and blistered on all sides, 10 to 12 minutes total. Transfer to a bowl, cover with plastic wrap and let steam for 10 minutes to loosen the skins. Discard the foil.

Reduce oven temperature to 350 degrees F.

Place hazelnuts on the baking sheet and toast in the oven until fragrant, 10 to 15 minutes. While still hot, wrap the nuts in a clean kitchen towel and rub until most of the skins are removed. Toast the almonds on the baking sheet until fragrant, 8 to 10 minutes.

Drain the chiles; remove stems and seeds and coarsely chop. Peel the roasted peppers, remove seeds and thick membranes and coarsely chop.

Place the hazelnuts, almonds, bread and garlic in a food processor; pulse until finely ground. Add the chiles (or ancho powder, if using) and peppers, vinegar, tomato paste, paprika, salt and cayenne; process to combine, stopping to scrape down the sides as needed. With the motor running, add oil and process until the mixture is well combined. Let stand at room temperature for up to 2 hours or cover and refrigerate for up to 2 weeks.