Here's how I make Khandvi/Surali Chi Vadi:
Stuffing - 1 cup frozen shredded coconut, handful of cilantro, 1 or 2 green chillies, ginger paste, salt, sugar and lemon juice. Coursely grind the ingredients together. Or finely chop and mix.
Other prep - Spread 3 or 4 sheets of aluminum foil on the counter top. For each keep 1 katori ready. Wet the bottom of the katori with little water.
Khandvi rolls - 1 cup gram flour, 2 cups thin buttermilk, pinch of hing/asafetida, salt and sugar to taste. The buttermilk should preferably be a little sour. Leave it out for a couple of hours before use. Sieve the gram flour, then mix all the ingredients together. Whisk together to get a smooth batter. Put this in a heavy bottom pan and place on the stove on medium heat. Keep whisking as it heats up. In 5 mins., the batter will start to thicken. Whisking will become harder, but its important to keep doing so, to break lumps and keep the batter smooth. In another 3 mins or so, batter will start leaving sides of pan and will acquire a little sheen. This is when it is ready to spread on the foils. You can test by putting a little drop at first. Wait a minute, then try to roll it to see if its ready.
Once the batter in ready to be spread, it is time to act fast. Take off heat, drop a ladleful of batter on one foil. Using the moistened katori bottom, spread it as evenly and thinly as possible on the sheet. Use gentle pressure when doing so. Keep ladling the batter on all the foils, spreading as you go, before moving to the next ladleful.
Once all the batter is spread, let it rest for a few minutes.
The one step I am still working on is spreading the batter fast enough. I still end up wasting some batter which cools down before I can spread it.
As the spread batter cools, make tempering with oil and mustard seeds.
Spread the coconut stuffing and the tempering evenly on the spread batter. Then start cutting strips about 1.5 to 2 inch wide. Roll from one end to the other. Note that you will need to trim edges to get even shaped strips.
Serve at room temperature. These will be gone in minutes, so be sure to save a couple for yourself.