Wash and soak the parboiled rice, urad dal and fenugreek seeds in a deep bowl in enough water for 2 hours. Drain and keep aside.
Wash and soak the barley separately in a bowl in enough water for 2 hours. Drain and keep aside.
Combine the parboiled rice, urad dal, fenugreek seeds and and barley in a mixer to a smooth paste using little of water.
Transfer the paste into a bowl, add the salt and mix well. Cover it with a lid and keep the batter aside to ferment for 4 hours. After fermentation, mix the batter well once again. Now add eno. Mix well.
Grease the idli moulds with a little oil and pour spoonfuls of the batter into each of the idli moulds. Sprinkle a few mixed vegetables over each idli.
Steam in an idli steamer for 15-20 minutes or till they are cooked. 
Serve hot with Sambhar & coconut chutney.
