Preheat oven to 350F.

Place coriander and cumin seeds in a shallow baking pan.

Roast in the middle of the oven for 5 minutes, or until fragrant.

Remove from oven and let cool slightly.

In a bowl, combine roasted coriander and cumin seeds with red pepper flakes, turmeric, ground ginger, black peppercorns, cardamom pods, cloves, and cinnamon stick.

In batches, grind the spice mixture to a powder using a spice grinder.

Store the masala in an airtight container for up to 6 months.