Heat oil in a pan/kadhai on medium heat, when hot temper it with cumin seeds.
When the seeds splatters, add the grated ginger and chopped green chillies and saute for few 10-15 seconds.
Now add in the boiled mashed potatoes and mix.
Now add in the boiled mashed potatoes along with turmeric powder, chilli powder, garam masala powder, aamchur powder, salt and mix everything together and saute.
Next add in the green peas, raisins and chopped cashewnuts if using and and mix it well with the potatoes and cook for few minutes.
Next add in the coriander seeds and coriander leaves and mix everything well and cook for furter 1 minute. Take it off the heat and let it cool.