In a wok heat 1 Tbsp ghee add the chopped ginger and green chillies and fry for a minute. Add the potatoes and stir. Add the coarsely grounded powder, asafoetida, black pepper powder, turmeric powder, red chilli powder, aamchur powder, salt and mix well with the potatoes on low heat. Cover for 4-5 mins. Let the potatoes overcook a little. Stir and set aside. Refrigerate the samosa filling.