Heat the oil in a kadhai or deep pan. Add the onions, green chillies, ginger and garlic to the oil and sauté till the onions turn golden brown. Add the turmeric powder, red chilli powder and the Punjabi Garam Masala to this and stir well.
Add the tomatoes and let it cook well till the oil rises above it. Now add the chicken pieces. Add just a little bit of water so that it doesn't stick to the bottom of the pan. Remember that chicken will give out water when it cooks, so you don’t want too much water in the curry. Just about a ¼ cup will do.
Add salt and keep stirring every once in a while till the chicken is cooked well and you have a thick sauce of the tomatoes, onions and the spices.
Garnish with cilantro and serve hot with chapatis or rice.