Heat ghee in a non-stick saucepan. Add sliced onion along with curry leaves and green chilies. Fry the onion until golden on medium heat. This will take about 4 to 5 minutes.
Slightly lower the heat and add spice powders like 1/2 tsp of turmeric powder, 1 tsp of coriander powder, and 1/2 tsp of cumin powder. Fry well on low heat for 2 minutes.
Add marinated chicken pieces and stir fry with spices on high heat for 1 or 2 minutes. Keep stirring to avoid the chicken and spices from sticking to the pan.
Cover and cook on low flame for 5 minutes. Then open the lid, stir a little, and add 1 cup of boiling hot water.
Let the chicken pieces cook well on low flame for 15 to 20 minutes or until the chicken is fully done.
Once you feel the chicken is almost cooked, add diced capsicum or 4 large non-spicy green chilies and 1 tbsp of grated jaggery.
Taste and add more salt if needed. Stir well for 2 minutes and cook until the capsicum slightly softens.
Garnish with coriander leaves and serve hot with roti, naan, or Paratha.