Mix all the ingredients in a bowl and let it rest for 5 minutes.
Brush Idly moulds with oil. Pour about 1-½ tablespoon of batter on each mould. Then, microwave it for 3.5 minutes to 4 minutes. If you were steaming it on a stovetop, it would take about 10 minutes, depending on the size of the Idly moulds.
Notes
You can make the batter in advance, even the night before and let it rest in the refrigerator.
Unlike rice Idly, these semolina Idlis will not rise. However, it will still be fluffy and soft.
Once steamed, remember to take out the Idly from the microwave. I had kept it inside for a longer time once and eventually, it got dry and hard.