Heat the oil in a large saucepan or wok
Add the mustard seeds and, when they crackle, add the asafetida, if using, then add the onions, turmeric, cayenne, if using, coriander powder, and coriander leaves.
Saute for a few minutes until onions start to just brown.
Add the tomatoes and garam masala. Let the tomatoes release most of their liquid.
Add the uncooked, sprouted beans (precook the beans only if you use a larger bean like a chickpea or a kidney bean). Add the coconut and stir well.
Add 1 cup of water, bring to a boil, cover and let the curry cook about 30 minutes or until the beans are cooked. If you want more sauce, add more water.
Add the lemon juice.
Add salt to taste. Garnish with more coriander if you wish.
Serve hot with chapatis or rice.