Wash and soak the chana dal in water for at least an hour. Drain and keep aside.
Add 2 cups water to the soaked dal and pressure cook for 10 to 15 minutes, till the dal is cooked.
Heat the oil in a non-stick pan, add the cumin seeds and allow them to crackle.
Add the cooked dal, ginger-green chilli paste, turmeric powder and chilli powder and cook for 2 to 3 minutes.
Add the cucumber and salt and simmer for 10 to 15 minutes till the cucumber is tender, but still a little crisp. Add some water, if required to adjust the consistency.
Garnish with the coriander and serve hot with rice or chapatis.