Line a rimmed baking sheet with parchment paper. Place the chicken chunks in a single layer on the parchment. Cover them with a second layer of parchment paper or line out a second sheet separately. Place the onions even across this layer. Lastly, place the garlic and ginger in a pile/mound on top. Freeze until solid, at least 4 hours. *This step and the following step I did a few nights before.
After they freeze, place the onion, garlic, and ginger inside a quart sized freezer bag. Place the chicken inside a gallon-sized freezer bag and place it in the freezer.
When you are ready to cook this meal, be it the next day or 1 month later, simply take everything out of the freezer. Put the Instant Pot on sauté then add the oil and contents of the onion packet. Cook until brown; stirring occasionally. If using a stovetop pressure cooker; between 8 and 10 minutes.
Add the curry powder, 2 tsp of salt, turmeric, cumin, and 1/4 tsp of pepper and cook; just stir occasionally. Then add the water and half of the frozen chicken. Stir until they are coated in the sauce then add the remaining chicken. Stir in all of the chicken until they are all coated in the sauce. Finally, add the potatoes; stir to combine all ingredients..
Cover and lock the lid. Place on HIGH pressure. Cook on HIGH pressure for 15-18 minutes and let the pressure release naturally.
Place over steamed rice, add cilantro, and serve.