In a wide pan, lightly heat up the oil, and add black mustard seeds.
When the mustard seeds start crackling, add the curry leaves, and red chilies (each slit in two parts), and roast for 1-2 minutes, till they get lightly roasted.
Then add in the chopped onions & salt, and saute on medium flame, till the onions start to turn light brown (~ takes about 7-8 minutes).
After this, add in the ginger garlic paste & saute for 2-3 mins, just till it loses its raw flavor.
Finally add in the marinated chicken thigh pieces & mix well.
Cook covered on medium high heat, stirring intermittently, till the chicken is fully cooked ( ~ takes about 25-30 minutes).
Serve this chicken kali mirch (pepper chicken dry) hot.