• Wash and soak rice in water for 2-3 hours. After the soaking time, drain the water, take the rice along with watermelon rind, coconut, chilies, curry leaves and ginger.
• Grind it to a smooth batter. I used my mixer and ground the batter in  batches. Take care not to grind all at once, your mixer might conk off. So, divide the ingredients into two batches and grind.
• I didn't add any water to the batter while grinding, the watermelon rind has enough water to help in grinding. After grinding, remove the batter to a clean vessel.  Let the batter sit for 15 minutes.
• Add chopped onion, salt, cumin seeds and ginger to the batter and give it a good stir.

To Make the dosa

• To make the dosa, heat a tava/pan, add a teaspoon of oil to the tava when it is hot, wipe it well with a tissue or a cloth. Pour a ladle of batter in the center, spread a little, but, not too thin.  
• Dot the edges with gingely oil,make a hole in the center and add lil oil there too. Cover and cook for a minute.
• Flip the dosa, and cook the other side for another minute. Remove the dosa on to a  serving plate, serve hot along with any chutney of your choice.
• I served it with Karivebu soppina chutney/curry leaves chutney