Soak the chana dal and tuvar dal in water for at least an hour. Then grind to a paste with cumin seeds, red chilies, turmeric and salt, using as little water as is feasible.

Transfer the paste to a microwave-safe bowl and zap for two minutes. Take it out, turn it around with a fork, and microwave the other side for another minute. The paste should have solidified by now. If it hasn't, microwave it until the paste is set. Set aside.

Cook the green beans until just tender.

Heat the oil in a cast-iron or other skillet.

Add the mustard seeds and, when they pop, add the udad dal and asafetida.

When the udad dal turns lightly brown, add the beans and stir to coat.

Now crumble the ground lentil paste into the pan. Stir, breaking up any bigger pieces with the ladle. Cook until the crumbled lentils starts to turn just lightly brown and no longer taste raw.

Serve hot!