Wash and soak for 5 hours the bengal gram dal in water.
Discard the water and grind to a fine paste the chana dal with green chilli.
Heat oil in a thick wok and add the mustard seeds once they splutter add turmeric, asafoetida and the dal mixture and stir it well
Sauté the mixture stirring it at frequent intervals. Take care the mixture should not stick to the bottom.
As the dal starts drying out add the salt and the coconut, if using, and sauté on medium heat.
Your watli dal is done when the mixture dries out and each grain is separate.
Serve garnished with coriander leaves and freshly grated coconut. I like some lime with mine.
Notes
My friend Varada grinds her dal with milk. That sounds like a great way to get a smooth paste.
Keep the flame medium-low and stir frequently. We do not need the dal sticking at the bottom of the pan. Avoid the temptation of raising the heat all throughout the process of cooking.
Psst, the stuck dal tastes the best!
Now, if you are unable to finish the full dal store it in an airtight container in the fridge. Lasts for 2-3 days.
Now you can scale up or down the ingredients given.