To sprout the mung beans:
Soak mung beans in water for 8–12 hours. Drain water and keep covered in a container that does not allow light for about 12 hours, or until the beans have sprouted.
To make the salad:
Mix sprouted beans, cucumber, tomato, and chopped cilantro. Add juice from 1 lime. Temper mustard seed, turmeric, and asafoetida with ghee, until the mustard seed begins to splutter. Pour the tempered spices into the salad, then mix thoroughly. Season with salt just before serving. Best served chilled.