Soak uradh dal 5hrs.Then grind it with ginger and chilly into very thick paste.Now mix chopped onions and curryleaves salt.Smear your palms with water.Take a ball of the paste and hold in ur left hand.with ur right hand make a hole into it.Deep fry them to make vadas.By the time season curd with fried mustard,cumin,curryleaf,chillies.Add enough salt to curd.Now pour the curd over vadas.Press the vadas so that curd gets into it....the dish is ready