Oil a flat tray (baking pan) and set aside.
Put the gram flour, yoghurt, ginger paste, turmeric, green chili paste, chili powder, and 250ml / 8fl oz (1 cup) water in a bowl. Season with salt and stir until it is a smooth paste.
Pour the mixture into a kadhai or wok and cook for about 10 minutes, or until it is thick in consistency, then spread the mixture evenly over the prepared tray (pan) and allow to set.
When the mixture has been set, use a rolling pin to roll from one end to another, then cut it into 3-cm / 1 1/4-inch pieces and set aside.
Heat the oil for the tempering in a small, heavy-based frying pan (skillet), add all the tempering ingredients, and stir-fry for 1-2 minutes or until the spices smell fragrant.
Pour the spice mixture over the gram flour pieces and serve.