Dry Roast the lentils - In a pan, dry roast the toor dal and chana dal separately till aromatic and light golden. Set aside.
Roast spices - Roast coriander seeds, red chilies, black peppercorns, cumin seeds individually till fragrant. Roast curry leaves last.
Let cool - Transfer everything to a plate and let cool completely.
Grind - Grind the roasted ingredients to a fine powder in mixer. Store in an airtight container.