Cut the potatoes into chunks.
Roast the cashew nuts lightly and grind into a coarse powder.
Whisk the yogurt till its smooth.
Heat oil in a saucepan over low heat.
Add garlic, chilli and ginger paste and stir fry till the garlic is light pink in colour.
Add the ground masala. Stir for 30 seconds.
Add the cashew nut powder and salt. Mix well.
Stirring constantly, add yogurt. Keep on stirring till the gravy becomes a bit thick.
Add the potatoes and water.
Let the curry simmer over low heat for 5 minutes. Don't forget to stir it occasionally.
Garnish with fresh coriander and serve with rice, rotis, parathas or naan.