Dissolve corn flour in 2 tablespoon (tbsp.) of water.
Chop drumstick into 1 inch pieces.
Grind ginger, garlic, tablespoon (tbsp.) of water into a fine paste.
In a pressure cooker add tomato, green chili, onion, ginger, garlic, salt, garam masala, 2 1/2 cup of water. pressure cook this for 3 to 4 whistle. Once the pressure is gone stain the vegetables from the soup.
Mash the vegetables, add 1/2 cup of water. filter the water and add to the soup.
Heat the soup and bring to boil. Now add the dissolved corn flour and cook for 3 minutes.
Now add the mint leaves, coriander leaves and remove from heat.