Steps:

• Combine the pineapple juice with the corn starch to make a slurry, and set aside (this will be used to thicken the sauce later).
• Stem, pit and slice the cherries in half. Extract the cherry juice by combining the prepared cherries with 3 tablespoons of water in a small saucepan.
• Simmer over low heat until the fruit softens. Gently mash the cherries with a potato masher, and continue simmering until the juices are released.
• Strain and discard the solids. Measure out 1/8 cup of cherry juice (add more water if needed).
• Add the cherry juice, ketchup, vinegar, and soy sauce to the saucepan. Heat and stir over medium heat until combined.
• Add the sugar and continue simmering over medium heat while stirring. Taste and add more sugar if you want a sweeter flavor.
• Once the sugar is dissolved, stir the pineapple juice slurry, and add it to the saucepan.
• While stirring, bring the saucepan to a boil over medium-high heat.
• Reduce the heat to low and simmer until the sauce thickens, about 5 minutes.
• Remove the pan from the heat and allow the sweet and sour sauce to cool. Makes about 2 cups.
• Use immediately, or store the refrigerator for up to a week, or freeze for up to 4 months.

Steps:

• Mix the sugar, vinegar, maraschino cherry juice, and pineapple juice in a saucepan over medium-low heat, stirring to dissolve the sugar.
• Place the cornstarch in a small bowl, and stir the water into it to make a smooth paste. Stir the cornstarch paste into the juice mixture, and bring to a simmer. Stir constantly until the mixture thickens, about 1 minute.