Cut idli into 1" cubes.
Deep fry them in hot oil until crisp.
Drain oil and transfer to a plate. Set aside.
Heat oil in a pan and add mustard seeds and curry leaves.
Add grated ginger and garlic and sauté for a minute or two.
Add onions and sauté until translucent.
Add tomatoes and cook covered until it turns mushy.
Add turmeric, sambar powder and salt.
Cook for a minute or two on low flame.
Add 1/4 cup of water and cover and cook for two minutes.
Add the fried idlis in the curry and mix well.
The idlis must soak up the liquid. They should also retain the crispness, so have little gravy in the curry. Too much liquid will make it soggy.
Add coriander leaves and serve immediately.
