Heat the vegetable oil in a pan. Once oil is hot add mustard seeds and half the curry leaves. Let it splutter.
Add Onions. Once it starts to change color add the green chillies, ginger and garlic. Saute until the raw smell leaves
Add the red chilli powder, coriander powder and jeera powder. Saute on low-medium heat for 3-4 minutes.
Now turn the heat to high and add the marinated chicken. Saute on high heat for 3-4 minutes to seal the chicken with all the spices and the chicken gets a light brown color.
Now add half cup of water to the chicken, scrape any bits stuck to the bottom of the pan, cover with lid and let the chicken cook for 5-8 minutes. Stir ocassionally making sure there is enough water.
When the chicken is cooked half way through add the chopped tomato. Combine everything well, cover and cook until chicken is completely cooked and tomatoes are completely dissolved.
Now add the Garam Masala and Fenugreek Powder. Combine well and add salt to taste.
Add coconut milk and cilantro. Bring to boil and immediately switch off flame.
To temper: In a small pan heat the coconut oil. Once hot add the mustard seeds, remaining curry leaves and dried red chilies. Let it splutter.
Pour over the chicken curry, cover the lid and let it sit for 10 minutes before serving.