Heat 1tbsp oil in a pan, add the chana dal and dry red chilies. Saute till the dal turns golden and the chilies turn dark.
Add the onions, tomatoes, green chilies and garlic cloves. Cover and cook till the tomatoes are mushy, about 10~12 minutes.
Add the tamarind paste, salt and cook for another 3~4 minutes. Take off the heat and let the mixture cool completely.
Grind the tomato mixture until smooth. Add the mashed avocado and grind till everything is combined. Remove into a bowl.
Heat 1tsp oil in a small pan, add the mustard seeds, urad dal and curry leaves. Once the seeds start to splutter, add the tempering on the chutney. Serve with rice, idlis, dosas or even upma.