Combine the pineapple juice, rice vinegar, ketchup, brown sugar, soy sauce, garlic powder, and ground ginger in a medium saucepan. Whisk until the brown sugar dissolves.

Place the saucepan over medium heat and bring the mixture to a gentle simmer, stirring occasionally for about 3-4 minutes.

Prepare the cornstarch slurry by mixing cornstarch and water in a small bowl until smooth.

Once the sauce simmers, slowly pour the cornstarch mixture into the saucepan while whisking constantly.

Continue cooking for 2-3 minutes, stirring frequently until the sauce thickens and coats the back of a spoon.

Remove from heat and let cool slightly. Adjust sweetness or tanginess as needed.