In a medium nonstick saucepan, combine pineapple juice, ketchup, brown sugar, vinegar, and soy sauce, whisking to combine.

In a small bowl, whisk together cornstarch and water to make a slurry.

Add slurry to pineapple-juice mixture, whisking to combine. Bring to a low boil over medium-high heat, whisking often. Reduce to a simmer, whisking often. Cook for 3 to 4 minutes or until thickened. Add Sriracha, stirring to combine. Remove from heat, and let cool for 20 minutes.