Heat a wide pan on medium flame, add oil, once hot add mustard seeds, allow to sputter, then chana dal, urad dal and saute for a few seconds.
Next add green chillies, chopped ginger, sliced onions and some curry leaves.
Measure and add water, some salt to cook the onions, add Turmeric powder and cook until the onions are translucent.
Once the onion looks soft and translucent, and the mixture comes to a gentle simmer.
Add the crushed potatoes and mix it in the pan, use the back of your spatula and mash it down further to bring a masala consistency. Check for salt add to taste.
Cover and simmer until the flavours are infused in the potatoes. This should take about 10 minutes on medium flame.
Mean while, add a little water to the chickpea flour and keep the slurry ready.
Now, open the lid and add the prepared chickpea flour slurry.
Mix well and cover and cook for 5 more minutes on medium flame. Until the masala is bubbling.
Garnish with fresh corriander leaves and serve hot with Poories.