Add the apricot jam, pineapple juice, ketchup, rice vinegar, soy sauce, and garlic powder to a small saucepan.
Place the saucepan over medium heat and whisk until the ingredients are fully combined and the mixture begins to simmer.
In a small bowl, mix the cornstarch with the cold water until completely smooth.
Slowly pour the cornstarch mixture into the simmering sauce while whisking continuously.
Cook for 1–2 minutes, stirring constantly, until the sauce thickens and becomes smooth and glossy.
Remove the sauce from the heat and allow it to cool slightly before serving. It will continue to thicken as it cools.