Make the Spice Paste: Heat 2tsp oil in a pan and add chana dal, urad dal, coriander seeds, dry red chilies, asafoetida and fry till they are fragrant and turn lightly golden. Let the mixture cool and grind into a paste along with coconut and tamarind.
Steam or microwave the beans until tender. Keep ready.
Heat 1tbsp in a saute pan, add mustard seeds, chana dal, urad dal, cumin seeds and dry red chili. Once the seeds start to splutter, add curry leaves and the ground paste. Cook on low heat, stirring frequently until the mixture is dry and crisp, about 4~5 minutes.
Next add the cooked green beans and salt. Mix well, cover and cook for about 4~5 minutes for the flavors to meld. Serve hot with rice.