In a bowl, combine wheat flour, sooji, rice flour and salt. Mix well.
Next add the yogurt and enough water to make a thick batter. Make sure to whisk well to make sure that there are no lumps in the batter.
In a small pan, heat oil and add urad dal, mustard seeds and cumin seeds. Once the seeds start to splutter, add hing, curry leaves, ginger and onions. Cook till the onions turn translucent. Season with salt. Do not add too much because the batter already has salt in it.
Add the onion mixture to wheat batter along with cilantro and mix well.
Heat the appam pan, add about ½tsp oil in each hole. Add about 1~2tbsp of the batter, cover the pan and cook the paniyarams until golden brown. Gently flip and cook until golden on the second side.
Remove and serve with your favorite chutney.