For the filling, dissolve the asafoetida in 2 tablespoons of water and set aside.
Cook the potatoes in a pan of boiling water for about 20 minutes, or until soft, then drain and allow to cool.
When the potatoes are cool, peel off their skins, return to the pan and mash.
Cook the peas for the filling in a separate pan of boiling water for about 5-7 minutes, or until soft, then drain, return to the pan and mash. Set aside
Put the mashed potatoes, spices, mint, chillies and coriander in a bowl and mix well.
Divide into 12 equal portions and roll into balls.
To make the filling, heat the ghee in a pan, add the cumin seeds and stir-fry over medium heat until they begin to splutter.
Add the reserved asafoetida, the ginger and chillies and stir-fry for a few seconds, then add the mashed peas and stir-fry until the mixture becomes dry.
Remove the pan from the heat and stir in the amchoor and black pepper.
Adjust the seasoning and allow to cool.
When the mixture is cool, mash with a potato masher and divide into 12 equal portions.
With damp hands, flatten each potato ball to make round patties.
Place a portion of the filling in the middle, roll into balls again to enclose the filling and then flatten to make 1-cm / 1/2-inch thick round patties.
Heat the ghee for shallow-frying on a thick tawa or flat griddle or in a frying pan (skillet) over medium heat.
Working in batches, add the patties and shallow-fry, turning once, for about 3-5 minutes on both sides, or until a thick crust is formed.
Remove with a slotted spoon and drain on kitchen paper (paper towels).
Cook the remaining patties in the same way.