Ingredients

　　1 onion, quartered

　　1 1/2 cups distilled white vinegar

　　1 cup ketchup

　　1/4 cup apple juice

　　1/4 cup firmly packed dark brown sugar

　　1/4 cup vegetable oil

　　2 small garlic cloves, chopped

　　1 sweet pickled gherkin, chopped

　　2 tablespoons bottled sweet pickled gherkin juice

　　2 tablespoons Dijon-style mustard

　　1 1/2 tablespoons ground celery seeds

　　1 1/2 tablespoons Worcestershire sauce

　　2 tablespoons Tabasco

　　1 1/2 teaspoons cayenne, or to taste

　　1/2 teaspoon turmeric

　　In a blender or in a food processor fitted with the steel blade purée the onion with the vinegar, add the ketchup, the apple juice, the brown sugar, the oil, the garlic, the gherkin and gherkin juice, the mustard, the celery seeds, the Worcestershire sauce, the Tabasco, the cayenne and the turmeric, and blen the mixture until it is smooth. Transfer the mixture to a stainless steel or enameled saucepan, bring it to a boil, stirring, and simmer it, stirring, for 20 minutes. Let the sauce cool. (The sauce may be prepared up to 1 week ahead and kept covered and chilled.)