Take the rice flour in a wide bowl and the add sesame seeds, butter, ajwain and salt. Mix well.
Add required water to make a smooth dough. Keep it covered till use.
Take the murukku mould and fill it with the dough.
Squeeze out the dough in a spiral fashion.
Heat oil in a kadai and check its temperature by dropping a pinch of dough.
Reduce the flame to low and put 3-4 murukkus.
Cook both the sides till the murukku turns golden brown on both sides. Note that if the oil is not hot enough, the murukku will absorb more oil. So adjust the heat and make the murukku in batches.
Store in an airtight box after it cools down completely.