Romesco is a rich Spanish sauce of charred tomatoes and roasted red peppers, puréed and thickened with toasted almonds and bread. The flavors are further sharpened with the addition of raw garlic, vinegar, chile powder or red pepper flakes (adjust the heat to your liking). The result is a smoky, pungent sauce, one usually served with mild-mannered vegetables and fish. (Some Spaniards say that a grilled vegetable feast is just an excuse for eating romesco.) But the sauce is just as good on a piece of toast that’s been brushed with olive oil and rubbed with yet more garlic. If you have the time, let the sauce stand for an hour at room temperature before serving, allowing the flavors to meld all the more.