Chop the idlis and keep aside. make bite sized pieces and do not chop finely.
finely chop 1 medium sized onion and 1 medium to large sized tomato. keep aside.
also chop 1 green chillii. keep aside.
also crush ½ inch ginger (adrak) + 3 to 4 garlic (lahsun) to a paste in mortar-pestle. keep aside.
making masala idli recipe:
heat 1 tbsp oil in a pan. add 1/4 teaspoon cumin and let them crackle.