Heat oil in a pan or kadhai over medium flame. When hot, add chana dal, urad dal, mustard seeds, and cumin seeds. On medium flame, fry till dals starts to change color.
Next, add slit or chopped green chilies, curry leaves, dry red chilies, and asafoetida. Fry for a few seconds.
Add the sliced onions, and saute till translucent.
Add the crushed ginger, garlic, and green chilly. Saute for 1-2 minutes or until the raw smell goes away.
Add turmeric powder and salt. Saute for a minute.
Now, add boiled potatoes. Break them with a ladle and saute for about 2-3mins.
Add 2 cups of water and mix well. Turn the flame to high and cook for 5 minutes.
Turn the flame to low, add the besan slurry and mix well.
The curry will start to thicken.
Taste for seasoning and adjust accordingly. Cover the pan and simmer the aloo curry for at least 10 mins.
Remove the cover and add coriander leaves.
Mix well. Poori Masala is ready. Serve hot with pooris.