Prep chicken by cutting it into small bite size pieces. In order for everything to cook at the same rate they need to be small.
Add broth, soy sauce, brown sugar, sesame oil, rice vinegar, salt and pepper to the Instant Pot. Mix well. Add diced chicken, broccoli florets, carrot shreds and garlic. Mix to combine.
Place the lid, close steam valve and seal both shut. Cook on high pressure for 3 minutes. When cooking is complete, quick release the pressure. Carefully remove the lid and use a slotted spoon to remove the chicken and broccoli mixture, leaving the liquid in the instant pot.
Set the instant pot to saute and bring mixture to a boil. Whisk together in a small bowl the cold water and cornstarch slurry until smooth, add into sauce to thicken. Once thick, a few minutes, turn pot off and return meat and broccoli to coat. Serve.