Now take a wok. Add cooking oil and put cumin seeds and when cumin seeds splutter put finely chopped garlic and saute for 30 seconds on low flame. Add grated ginger and saute for 30 seconds. Add chopped onion and cook till translucent. Add tomato puree and cook till oil leaves the karahi. Add salt, red chilli powder, turmeric powder, garam masala and chana masala and mix well