Heat a pressure cooker and add oil. When oil is hot, add cumin seeds, fennel seeds, asafoetida and let it sizzle.
Add the ginger-garlic paste and fry for a minute. Then add onion and fry till the onions turn golden brown.
Add the tomato, green chillies, mint leaves, turmeric powder and cook till the tomatoes are soft and mushy.
Now add the potatoes, curry powder, black pepper, salt , 1 1/2 cup water and combine. Cover and pressure cook for 2 whistles.
Add the coconut milk powder and cook for another 1-2 minutes. Remove from heat and add the coriander leaves.
Notes
Curry powder gives a unique flavor to the curry. If you do not have curry powder, substitute with 1 teaspoon coriander powder and 1/2 teaspoon garam masala.
Coconut milk powder enhances the flavour of the overall curry, but if you don't have coconut milk or powder you can skip it.
Reduce the amount of spices and chillies for a milder curry.
You can also make the curry in a kadai or pan. Add boiled potatoes to the onion-tomato mixture and water as required.
If you want thick curry or if curry is watery, mash some of the potatoes and cook for few more minutes.