Soak the urad daal + methi seeds / fenugreek seeds in water for about 4-6 hours.
Once soaked, drain the daal well (do not rinse with additional water). Add the urad daal along with the methi seeds and cooked rice in a food processor or mixer jar and grind by adding little water at a time as needed. (I used 1 and 1/4 cup water for grinding).
Pour this into a mixing bowl and add the rice flour. Add remaining water and mix well with your hands or a whisk. Remember to use a bowl which will have 3/4th empty space as the batter will ferment and can overflow.
Cover the bowl and place in a warm place, like a turned off oven or microwave to ferment for about 8-10 hours.
Add salt to the batter, mix well and pour the batter into idli moulds and steam it on medium high for 15 minutes.
Add coconut + coriander leaves + walnuts + chillies + garlic to a jar of mixer or food processor. Add little water as needed and grind it to a fine mixture. Pour into a serving bowl, add salt and adjust the salt as needed.
Add oil in a pan and place on medium high heat. Add mustard seeds. Once it crackles, add curry leaves and red chillies. Toss it or mix it and pour it over the chutney.
If in a hurry, you can soak the urad daal in warm water and grind it within an hour or two.
Its ideal to soak daal in the morning and grind in the evening so that batter is ready by morning or else soak daal in the evening and grind in the morning so that batter is ready by evening.