Thoroughly wash all the vegetables. Wipe the ladyfingers dry and slot them from the centre. Cut the ends of the cluster beans, peel the drumsticks, and peel and cut the potatoes in halves.
Boil the water in a large pan. Cut the tomatoes into halves and throw them into the boiling water. Boil till the tomatoes are soft - this will take about 10-15 minutes. This process adds to the flavour of the kadhi. Once it cools down, use a hand blender or masher to blend the tomatoes.
Sieve the tomato water. Add a little water and strain the residual tomato in the sieve. Ensure that no tomato skin goes into the sieved liquid.
Heat oil in a pan and add mustard seeds, When they begin to sputter, add cumin seeds and let them crackle.
Lower the flame to medium and add the chickpea flour to the oil. Stir continuously till it becomes dark brown in colour but not burnt. This will take approximately 7-8 minutes.
Add fresh coriander leaves, ginger, slit green chillies and red chilly powder. The green chillies will add heat to the kadhi while the red chilly powder will give it colour.
Now add water to the kadhi and stir. Add the sieved tomato paste and let the broth boil over a high flame.
After the first boil, add potatoes and curry leaves. Cook for 10 minutes.
Now add the salt and drumsticks, and cook for 10 minutes. Then add the cluster beans and cook for 10 minutes.
Add the ladyfingers and cook for 5 minutes. Now add tamarind water and cook for another 10 minutes.
Adjust the seasoning and serve hot with rice.