Take a heavy-bottomed pan and add chana dal, urad dal, cumin seeds, green chillies, garlic, and curry leaves. Roast everything on a low flame till the lentils are golden. Make sure that the green chillies are well-roasted and blistered. Roasted chillies taste really good in the thogayal. Once all the ingredients are roasted and golden, remove and set aside on a plate to cool. Leave the remaining oil in the pan.
To the pan, add the onions, tomatoes and the bottle gourd. I like to use peeled and diced bottle gourd. Add a small piece of tamarind, salt, turmeric powder and asafoetida. Mix well. Cover the pan with a lid and cook on a low flame for about 10 minutes till the bottle gourd is soft and mushy.
At this stage add the coconut and the coriander leaves. Cook for a minute. Do not cook for long after adding coriander leaves.
Take a heavy-duty mixie jar and add the roasted lentil chilli mixture. Grind to a smooth paste. Add little water while grinding. Once the mixture is ground to a smooth paste, add the cooked veggie mixture to the same jar and grind again. Grind to a coarse texture. Do not grind to a fine paste. Finally, add little jaggery and pulse once in the mixie. The texture of the chutney should be coarse. Remove the chutney to a bowl and set aside.
Take a small kadai and add little oil. Once the oil is hot, add the split urad dal and the mustard seeds. Let the mustard seeds crackle. Add the curry leaves and the dried red chillies. Roast for a few seconds. Add the tempering to the chutney and mix well.
Serve with rice and a little ghee. Enjoy!