In mortar-pestle crush green chilli, ginger and garlic together and keep it aside.
Heat a pan at medium heat and add oil. As oil turns hot add asafetida and cumin seeds.
As cumin seeds crackle add green chilli, ginger and garlic mixture . Mix well and cook till mixture turns pink.
Now add boiled and peeled potatoes and saute for a minute in garlic mixture.
Now add turmeric powder, red chilli powder, coriander powder, garam masala, dry mango powder, salt and mix well.
Cook till potatoes are slightly roasted and coated with masala. Keep steering it after every few seconds otherwise masala may burn.
When you smell nice aroma and potatoes are nicely roasted add coriander leaves. Give everything a nice mix. Garlicky potatoes are ready to serve. Serve them with pooris or parathas.