Heat the oil in a medium sized frying pan until the oil just starts to shimmer.
Stir in the garlic ginger paste. Gently fry until the garlic ginger paste stops sputtering. This can get a little messy.
Turn your heat down to medium low and add your spice mix and the remaining 5 curry leaves. Cook for about 30 seconds. You want to fry your spices in the oil. Don't skimp on the oil. Bad things happen if the spices stick and burn.
Add the green chilies. Cook another 30 seconds or so.
Add the Indian hotel curry gravy. Stir it really well to get the oil to combine with the curry gravy. You want everything mixed together at this point. Bring to a simmer.
Add the chicken thigh pieces in a single layer. Nestle them down into the sauce. Cover and cook about 5 minutes. Remove the cover, flip the chicken and recover. Cook until the chicken is done. Use an instant read thermometer if you have one. You are shooting for an internal temperature of 160F. It will get to 170F as the curry finishes cooking.
Add the tamarind paste and coconut milk. Stir well to combine.
Look at the consistency. If you are happy with it, cover and simmer for 2 minutes. If it's too thick, add a bit of water and stir to combine. If it's too thin don't cover it to let it reduce.
While the curry is in it's final simmer, warm up the tempering over low heat.
Transfer the kerala chicken curry to a serving dish and drizzle/sprinkle it with the tempering.
Kerala chicken curry is great with rice and chapatis or parathas.