Soak idli rice for 2 hours, then rinse and drain water.Grind it to a smooth batter using very less water in a grinder.You can use mixie too.Now take this batter in a mixing bowl.
Add urad dal flour,butter,salt and jeera.
Mix well so that the distribution of flour and butter is even.The batter shouldn't be very tight or too loose. It should be smooth and flexible,check my notes for more detailed information.
Grease your fingers with oil, keep a small lid on the cloth.Take a small lemon sized ball, bring one end to slightly pointing.
Roll it out using your fingers and stick it to the cap. Then gently using a twist and turn motion, roll out the dough into the shape of murukku.Now remove the cap and then move onto making the next murukku.Check my video.Similarly finish off the dough.I made some 10-15 murukkus then fried and again sat down to twist.
Heat oil in a kadai.Now using a flat laddle, take the murukku carefully and flip into preheated oil.
Fry until golden in low medium flame.Drain in tissue paper.Store in airtight container and enjoy.