Rub the ginger garlic paste, red chilli powders and turmeric along with salt on the chicken. Allow it to marinate for at least 30 minutes.
Heat oil in a saucepan. Add the chicken and fry both sides until just browned. It is not required to cook it fully. Drain and set aside.
In the same pan, add more oil if neede. Add the curry leaves and ginger garlic paste and saute for a minute.
Add the onions and as it gets browned, add the tomatoes and cook till oil seperates on top and the tomatoes are all mashed.
Add in the spice powders and salt. Fry for a couple of minutes. Add the fried chicken back into this sauce.
Squeeze out the tamarind and add the water. Add another 1/2 cup water and bring it to a boil. Adjust seasoning.
Cook till the sauce thickens and the chicken is fully cooked.
Finally add the black pepper and switch off. Garnish with more curry leaves and serve.