Cut French beans into half centimeter sized dices.
Cook beans in salted boiling water for two to three minutes. Drain well and reserve.
Finely chop green chilies.
Soak all the dals for about twenty-five minutes. Drain water and grind all dals to a thick paste with dry red chillies, salt and hing powder. Add water if required.
Apply a little oil on a piece of banana leaf according to the size of the steamer or the pressure cooker. Spread dal paste evenly on it and steam in a cooker for fifteen minutes or till cooked. Insert a toothpick or needle into the dal mixture and if it comes out clean then it is cooked.
Turn out cooked dal.
Crumble cooked dal to a coarse powder with your palm, if dal is quite dry and solid, then you can blend it.
Heat oil in a shallow pan, temper with mustard seeds, red chillies, urad dal and curry leaves.
Stir-fry briefly and add chopped green chillies.
Add the cooked beans and crumbled dal mixture. Toss on high heat for a two to three minutes. Reduce heat and cook, stirring frequently for five to six minutes or till the beans and dal start sizzling.