Soak 1 cup of chana dal in water for 2 hours, then drain well.
Coarsely grind 1 piece of cinnamon stick, 1in / 2.5cm long, 1 dried red chili, ¾ teaspoon of cumin seeds, and ¾ teaspoon of fennel seeds into a powder.
Pulse the dal with ½ teaspoon of salt to a coarse, textured mixture.
Mix in the spice powder, 1 medium chopped onion, 1 handful of chopped mint leaves, 1 sprig of chopped curry leaves, 1 chopped green chili, and 1¼ teaspoons of ginger garlic paste, until it holds together when pressed.
Divide into 10 portions, roll each into a ball, and flatten it into a patty.
Heat 2in / 5cm of oil in a deep pan over medium heat. Fry the vadas in batches until golden and crisp.
