Start with grinding the whole spices in mortar and pestle to a coarse powder. You can do the same in mixer as well but I stick to mortar and pestle for making spice powders in small quantity.
Next peel the potatoes, wash and pat dry them with a kitchen towel.
Cut each potato into equal halves.
Place one potato piece in between the kitchen towel and smash it with a rolling pin. The idea is to break the potato into uneven chunks. Similarly, smash the remaining potato pieces. Transfer to a bowl and set aside.
Heat oil in a cast iron kadhai (buy it here) over high flame. Once the mustard oil starts fuming, reduce the flame to low.
Add cumin, fenugreek and asafoetida. Stir for few seconds.
Add coriander powder, green chili, stir and then add potato chunks.
Fry the potato chunks for 3 - 5 minutes stirring occasionally in between.
Next add turmeric powder, red chili powder and salt. Stir to mix.
Fry the potato for 3 - 5 more minutes.
Add 1 Cup of water, cover the skillet with a lid and let the curry simmer over low heat.
After 10 minutes, open the lid and check potato for doneness. If potatoes are bit uncooked from the centre simmer the curry covered for few more minutes. If potato are cooked through, gently mash them with the back of the ladle.
Add the spice powder prepared in step 1 along with 2 Cups of more water. Aloo Paani as the name suggest is a watery curry so don't hesitate while adding water.
Simmer the curry for 10 more minutes uncovered over low heat.