Turn Instant Pot to "Saute" setting. Once pot is hot and reads "On" add onions. Cook for about 15 minutes until onions start to brown on the bottom of the pot. Add ginger, garlic and cut-up chicken. Saute another minute or two. Add carrots, potatoes, apple, curry powder, chicken broth, salt and pepper. Stir to mix well.
Press "Cancel" to stop saute process.
Press "Meat/Stew" and set timer to 15 minutes.
After timer goes off, either let Instant Pot naturally depressurize, or quick-release by turning steam release handle on the lid to "Venting" setting.
To thicken curry, mix together cornstarch and water. Turn Instant Pot to "Saute" mode. Stir in cornstarch slurry and cook a few minutes until curry thickens.
Adapted from Japanese Soul Cooking by Tadashi Ono