Heat the oil in a pan/wok add the garlic and ginger, fry for few minutes till lightly brown in color.
Add the sliced onions, green chilies and fry till the onions are lightly browned.
Now add the turmeric, coriander powder, red chili powder to the onions with few tbsp of water and fry at-least 8 minutes till the oil separates from the mix, this step is very crucial for proper flavor. Do not skip this.
Now add the chicken pieces and fry for few more minutes till all the water is dried up from the chicken.
Add the garam masala, fennel powder and salt and stir well to incorporate all the masalas.
Now first take few tbsp of coconut milk dilute with 1/2 cup of water and add to the chicken masala. Cook till the chicken is cooked or about 15 minutes.
Now add the rest of the coconut milk and the curry leaves.
Simmer on low heat for about 10 to 15 minutes with the lid closed. Switch off when it has boiled well and all the raw smell from coconut milk has disappeared.
Serve hot garnished with coriander leaves/cilantro