Pepper chicken

I had heard so much about my mother-in-law's pepper chicken, that I was petrified when she told me "Today, I will teach you to make pepper chicken", when we visited her the first time after our marriage. Me, who had never cooked non-veg food in my life. How was I worthy of possessing the Family Heirloom? What if I ended up poisoning the entire family? What if....
She brushed my fears aside, and told me that all pepper chicken required was five ingredients- vinegar, soya sauce, peppercorns, oil and salt. Though I don't think of either oil or salt as ingredients, I can "see" her counting the ingredients out everytime I get down to making pepper chicken.

1 kg chicken, cleaned
4 tbsps vinegar
2 tbsp soya sauce
2 tbsp peppercorns
cooking oil
salt to taste

Method
Coarsely grind the peppercorns, so some of them are ground well, some are merely broken and some remain intact.
Clean the chicken pieces, make a few slits in the flesh (if required) and keep aside
In a thick bottomed kadhai, mix all the ingredients together, and marinate the chicken for 30 minutes (you can skip this process if you don't have time, but it helps).
Turn on the fire, and when the mixture comes to a boil, turn the heat to the lowest, cover the vessel and let it cook in it's own steam. Turn the chicken pieces over every 15 minutes or so.
After 45 minutes, lift up the lid, let the gravy thicken (if required), and serve.