How to Make It
Whisk together chili sauce, jelly, soy sauce, mustard, and 1/4 cup of the water in a programmable pressure multicooker (such as Instant Pot) until blended. (Times, instructions, and settings may vary according to cooker brand or model.) Add meatballs, and stir to coat. Cover cooker with lid, and lock in place. Turn steam release handle to SEALING position. Select MANUAL/PRESSURE COOK setting. Select HIGH pressure for 8 minutes. (It will take 15 to 20 minutes for cooker to come up to pressure before cooking begins.)
Carefully turn steam release handle to VENTING position, and let steam fully escape (float valve will drop). (This will take 1 to 2 minutes.) Press CANCEL. Remove lid from cooker.
Select SAUTÉ and HIGH temperature setting on cooker, and, if necessary, allow to preheat 2 to 3 minutes. Bring sauce to a simmer. Whisk together cornstarch and remaining 2 tablespoons water in a small bowl. Stir cornstarch mixture into sauce. Cook, stirring often, until sauce thickens and glazes meatballs, 2 to 3 minutes. Transfer meatballs to a serving platter. Spoon sauce over meatballs, and garnish with scallions.