Heat oil in a large kadhai over medium flame. Add the cinnamon, cardamom pods, curry leaves and saute for few seconds till fragrant. Add the chopped onion and saute over low heat till onion is light brown in color.
Next add the tomato paste, salt, turmeric and fry the masala for 10 minutes or so over low heat. The indication of masala being ready is oil starts separating from it.
Now add the Chettinad masala paste and stir to combine. Continue to saute the masala scraping the bottom of the kadhai, till the masala takes deep brown color and nicely roasted.
At this stage add the chicken pieces, salt and stir coat the chicken pieces with the spice mixture. Fry the chicken pieces till they turn pale white in color. Do not add water.
Cover and cook the chicken over low heat till it releases its juices and full cooked.
Open the lid, check the chicken for doneness. At this stage, if you want to make gravy, add 1 cup of water or coconut milk, stir, and simmer the curry for 8 - 10 minutes.
Serve Chicken Chettinad Masala with rice or parotta.