Heat oil in a pan, add mustard and urad dal and let them sizzle.

Add in curry leaves and let them sizzle.

Add in onions, chilli and tomatoes. Cook that for couple of mins.

Now add in turmeric and salt and mix well.

Add in gram flour and toast for 2 mins on a low heat.

Now add in water and mix well. Bring this to a boil and simmer for few more mins.

Now add in salt, sugar, lemon juice and coriander leaves.

Serve this with idli or dosa.