This variety is also known as bullet idli. Its quite famous in South-Indian restaurants. Mini idlis are best served with piping hot sambar on it with some ghee. Try this unique recipe and let me know in the comments how it turned out.
Ingredients:
1. Raw Rice (Any Variety) – 2 Cups.
2. Whole Urad – ¾ Cup.
3. Cooked Rice – 2 Cups.
4. Cooking Soda – ½ Tsp.
5. Salt – 1 Tsp.
Method:
*Soak whole urad and rice after washing them well. Let it soak for minimum 4 hours.
* For example:, if the idly batter is for next day’s breakfast you have to soak the pulses in the afternoon only – it will be easier for you if you grind it in the evening the batter will be fermented by next day morning.
*After the soaking time, drain the urad and grind it finely.
*The paste should be fine but do not add too much water the batter will become runny.
*Remove the grinded urad in a vessel, now in the same jar add one part soaked rice and another part cooked rice.
*Grind it adding a bit water this batter should be a bit coarse. Add this to the grind batter.
*Now grind the remaining raw rice and cooked rice in the same manner. 
*Now mix the batter well with your hand. Allow the batter to ferment overnight.
*The batter will have risen in the morning.
Take a small bowl of water add the salt and cooking soda to it.
*Dissolve and add to the idly batter and mix well with a spoon.
*Take idly cooker grease mini idly moulds with oil and pour batter into each mould.
*Mini Idli moulds are easily available in the local market as well as online.
*Add one glass of water to the idly cooker and place the idly moulds.
*Cook for 10 minutes in high flame.
*After 10 minutes, switch off the gas.
*Remove the moulds from the cooker.
*Allow it to cool for a couple of minutes.
*Remove using a wet spoon.
*Your soft and fluffy mini idlis are ready.
*Serve along with piping hot sambar, chutney and ghee.
