Start by cutting the chicken into 2-3 inch chunks, I tend to leave them a bit larger as the pressure cooker tends to make the chicken very moist and this helps to avoid breaking the chicken pieces.
Heat up your pressure cooker: press Sauté -> click on the Adjust button -> select More to get the Sauté More function, which means that the food will be sautéed over medium-high heat. Wait for the Instant Pot indicator to read HOT.
Add the oil to the hot IP, wait one minute for the oil to heat up and add the chicken. Sauté for 2-3 minutes, stirring a few times. Cook until it just starts to get golden. This step can also be done on the stove if you want, as the instant pot doesn't really brown the chicken too well.
Add the rest of the ingredients to the pot: ginger, garlic, red pepper flakes, hoisin sauce, soy sauce, rice vinegar, brown sugar and water.
Stir well to combine.
Close lid, select the Poultry function and adjust the time to 5 minutes.
Use a 10 minute Natural Release. Turn off the heat. Release the remaining pressure. Open the lid. Gently stir not to crush the chicken.