Mix curd,sooji,water and salt in a mixing bowl to a smooth batter with no lumps(adjust the consistency using more or less water).

Keep the batter aside.

In a non-stick kadhai,heat a little oil.Add the mustard seeds.Let them crackle.Now add the chopped ginger and chillies.Add dal and let it turn to golden brown colour stirring continously at low flame.Further add the the curry leaves.Turn off the flame.

Add this temper to the previously made batter.Put baking soda into it and mix gently.

Now heat some oil in the same kadhai and put a tablespoonful batter into it.Do not overspread.Cover the kadhai with a small lid/plate.Cook it on a very low flame till the appam crisps from below for 2-3 mins.Flip the appam over and make it crisp from the other side as well.

Serve hot with mint sauce.