Heat 2 tbsp of oil in a pan.
Add the mustard seeds and allow them to splutter
Add chana dal, urad dal, and roast them until they are golden brown
Add curry leaves and let them sizzle
Add chopped ginger ,1 slit green chilly, sliced onions until the raw smell fades.
Add ½ tsp turmeric powder, 1 tbsp kashmiri chilly powder, 1 tsp garam masala (optional) and mix well.
Add the mashed potatoes, water , required amount of salt and mix well.
Adjust the consistency of the gravy by adding enough water.
If you want the gravy to be a bit thicker, dissolve 1 tbsp of gram flour in water and add it to this masala.
Adjust the salt to taste and garnish it with coriander leaves