Set the Instant Pot to saute mode. Add 4 tbsp oil, green chillies, ginger slices and whole dried red chillies. Allow to saute for a minute or so till they become fragrant.
Add the marinated paneer mixture. Saute for 5-8 minutes, stirring often till the paneer is heated through. Making sure to stir well so nothing is sticking to the bottom of the pan. You will see the oil start to come to the surface of the curry.
Add the potatoes, stir well to coat the potatoes in the curry.
Gently pour the rice with soaking water into the curry.
Add the raisins with soaking water, spreading them out in an even layer on top of the rice. Give it all a good mix making sure to scrape the bottom of the pan well. The liquid level should not be much more than 1 cm above the rice. If it looks like too much liquid discard some so you don't end up with biryani soup! ;)
Cancel saute mode. Close the lid, set the vent to sealing, and cook on high pressure for 6 minutes. Allow pressure to release naturally for at least 10 minutes. Then quick release any remaining pressure.
Once the pressure is released, open the IP lid and gently fluff the rice with a spatula or spoon a few times to break up the flat surface of the rice on top and mix everything together one more time. Be gentle so as not to break up the rice.
Sprinkle the top of the rice with the reserved brown onions, black pepper, cumin seeds and fresh cilantro. Cover again and allow to steam for 10 minutes in the residual heat before serving. Enjoy!