Heat four cups water in a steamer. Mix together the coriander leaves, green chillies, gram flour, yogurt, salt, turmeric powder and jaggery in a bowl. Add sufficient water to make a thick batter, ensuring that the consistency is not too thin. Adjust salt.
Pour the batter into a greased plate that is at least one and half inches deep or a tray measuring approximately six inch x six inch x one and a half inch. Place it in the steamer and steam on high heat for fifteen to twenty minutes or till firm and cooked.
Check by inserting a skewer into the wadi and if it comes out clean, then it is cooked. Remove, cool and cut into one-inch diamonds.
Heat the oil in a small non stick pan and add the sesame seeds, asafoetida and mustard seeds. When they splutter add the wadi and fresh coconut. Toss well.