Spinach Stems with Walnut Sauce

When thrifty Italian, Greek, and Turkish cooks clean spinach, they rarely discard the stems, as they can be served as a room-temperature salad dressed simply with olive oil and lemon juice. This recipe, which comes from Salonika, a Family Cookbook, has a Turkish name, but the nut sauce is Hispano-Arabic. (If it had a few minced cloves of garlic, the sauce would be a Greek skordalia.) In Moorish Spain, nut sauces were widely used, and almonds were the predominant thickener. Walnuts ar