In a pan, heat 1 tbsp oil and add ½ cup peanuts. Roast on low flame until golden.
Add ¼ cup roasted chana dal and roast lightly.
Add 4–5 green chilies, a few curry leaves, and 1 small piece of tamarind. Mix well and turn off the flame.
Transfer the mixture to a plate and let it cool.
Add the cooled mixture to a blender jar along with salt, a handful of coriander leaves, and ½ cup water. Grind to a smooth paste.
Transfer the chutney to a serving bowl.
For tempering, heat 1 tsp oil in a small pan, add ½ tsp mustard seeds and 2 dry red chilies, and sauté briefly.
Pour the tempering over the chutney and mix well.
Peanut chutney is ready to serve with rice dosa.