1/2 cup ketchup
1/2 cup rice vinegar or apple cider vinegar
1/2 cup pineapple puree (from Grilled Chinese Sweet and Sour Pork Kabobs)
2 teaspoons Worcestershire sauce
1/2 cup packed light brown sugar
2 teaspoons cornstarch
Stir together first 5 ingredients in a medium saucepan over medium heat. Combine cornstarch and 1 tablespoon warm water; whisk into ketchup mixture. Bring to a boil; boil 1 minute.