In a pot, add 100% pineapple juice 1 cup. (You can use the pineapple juice from the can, make sure to choose 100% pineapple juice.) After that, add 2 tablespoons of soy sauce, 2 tablespoons of vinegar, 3/4 cup of brown sugar, 3 tablespoons of ketchup, 1/4 teaspoon of salt. Mix it very well. Then, turn on a small & low fire and cook it until the sugar is melted. In a small container, add 3 tablespoons of cornstarch, 2 tablespoons of water and mix it well.  Next, pour the cornstarch mixture into the sauce to thicken it and set them aside. To find out details and step by step instructions, click this sweet and sour sauce recipe.