Firstly, take a mixer jar, add ½ cup besan, ½ cup curd, and 1 cup water.
Now add 1 inch ginger, 2 green chillies, ½ tsp salt, ¼ tsp turmeric, and blend it.
After blending, strain it into a pan and heat it.
Keeping the flame on medium, stir continuously and make it lump-free.
Cook for 4-5 minutes or until it thickens, and turn the flame to low.
After being perfectly cooked, turn off the flame.
Immediately pour it on a plate or a flat surface and spread it to form a thin layer. Let it rest for 5-7 minutes.
Meanwhile, heat 1 tbsp of oil in a pan. Add ½ tsp mustard seeds, 10-12 curry leaves, and 3 tbsp grated coconut.
Cook for 1-2 minutes on a low flame. Add a pinch of salt and mix well.
Filling is ready, turn off the flame, and let it cool.
After 5-7 minutes, make equal cuts horizontally using a knife. Spread the prepared filling and sprinkle some chopped coriander over it.
Roll it one by one carefully as shown.
Finally, enjoy khandvi with tomato ketchup.