To prepare the lentil flour, add 2 cups chana dal/Bengal gram to a pan and dry roast on low heat stirring frequently so that the lentils does not get burnt. As the lentils get roasted, the yellow colour deepens and you get the smell too. Remove and allow to cool well before grinding into a fine powder. Store in an airtight container.

Heat oil in a large kadai/deep bottom pan; add the mustard seeds and allow to splutter.

Next add the dry red chillies, curry leaves, ginger and garlic; sauté till the rawness of the aromatics goes away

Add the onions and sauté till light brown. Then add the tomatoes and cook till softened and mushy.

Next add turmeric powder, red chilli powder and the roasted lentil flour; mix well to combine and cook on low heat for 2 minutes.

Add 2 cups lukewarm water, season with salt and mix well. The mixture might feel lumpy at this stage but continue to cook on low heat for another 2 minutes.

Add the remaining 4 cups lukewarm water, mix well and bring to boil. Lower heat and simmer for 2 minutes before removing from heat. (adjust the quantity of water depending on how thick you want the curry to be).

Garnish with chopped coriander leaves and lemon juice.