Pour oil in a pan over medium heat and add mustard seeds / urad dal.
Let them splutter.
Add the sliced onion and slitted chilies to the pan.
Sauté until it turns pale.
Add the chopped tomatoes
Sauté it for few minutes.
Now add required amount of salt on to it.
Cook until they turn soft and mushy.
Add kulambu powder on to it.
Then add chilli powder.
Sauté it for a minutes.
Now add the tomato puree on to the pan.
Add 200ml water to achieve the desired consistency.
Allow it to boil for a couple of minutes.
In a small bowl, take the roasted gram flour
Add 2 - 3 tbsp of water to it.
Mix the roasted gram flour to form a smooth paste.
Slowly add this paste to the boiling tomato mixture while stirring continuously to avoid lumps.
Let it simmer for about 5-7 minutes until the raw smell of the gram flour disappears and the kulambu thickens.
Garnish with chopped coriander leaves and curry leaves.