In a heated frying pan (medium to high heat) add 1 tbsp of ghee.
Add the onions and stir until it becomes translucent. This should take about 3-5 minutes.
Turn the heat down to low. Add the chilli, garlic, and the ginger and stir it in until fragrant.
Turn the heat up to medium to high. Add the bay leaf, curry leaves, cinnamon, and mustard leaves. Stir this in for 3 minutes until the spices start to release their fragrance and flavour.
Add the all the spices EXCEPT the amchur (mango powder), salt and pepper. Keep stirring for 1 minute.
Turn the heat to low. Add the tomatoes. Stir it in and let it simmer for 5 minutes. No cover needed.
The tomatoes need to be mashable in order to go to the next step. If the tomatoes are hard, and you can't press it down (mash it up) with the back of your wooden spoon, keep stirring and cooking it through.
Stir in the mashed tomatoes with the spices thoroughly, to make a consistent masala mix.
Add the potatoes, and mix together until everything is integrated.
Add the 1 cup of hot water, mix and cover it with a lid. Let it simmer for about 45 minutes to 1 hour, until you potatoes become soft.
If you have not blended your fermented rice batter with the coconut mixture yet, this is the time to do that. You can also get started on the mint coriander chutney also.
After the potatoes are soft, and mashable, add the amchur, salt and pepper. Give it a taste, and adjust according to your salt/spice preference. Turn off the heat, leave the lid on and set aside.