Remove the green leafy parts from the stem and trim off half of the stem. Cut each eggplant lengthwise into 4 pieces along with the stem.
Peel and cut the potato into 1-inch cubes
Set the Instant Pot to saute mode and heat oil. Add mustard seeds and allow them to splutter. Add asafetida, garlic curry leaves, and turmeric. Mix well. Add potato, eggplant, red chili powder, cumin powder, coriander powder, and salt. Add water and give a quick stir.
Close the Instant Pot with pressure release valve to sealing. Pressure cook for 2 minutes followed by quick release. Open the Instant Pot, in case the eggplant are not fully cooked keep the lid closed for 5 minutes and they will continue to cook without having to pressure cook again.
Garnish with ground peanuts and cilantro. Give a quick stir and enjoy hot. Discard the stem while eating.