Heat 2tsp oil in a pressure cooker; add the chopped lotus stems and saute until crisp tender. Remove into a bowl and set aside.
In the same cooker, heat 1tbsp mustard oil and add cumin seeds and asafoetida. Once the seeds start to splutter, add the chopped spinach and salt. Cook until the water is evaporated, about 4~5 minutes.
Add the red chili powder, ground fennel and ground ginger. Cook for 1~2 minutes.
Add 1~1½cups of water. Cover the pressure cooker and cook for 2 whistles.
Once the pressure releases, mash the greens lightly with a spoon. Add the fried lotus stems and kala namak; cook for 5 minutes.