Mix yogurt, salt and pepper with ½ to ¾ cup water. Beat well and set aside.
Wash chicken and soak it in the above prepared butter milk for 2 hours to overnight in the refrigerator. Soaking for at least 6 hours is recommended to get soft chicken.
Blend and Make a paste of the ingredients mentioned for chili garlic sauce.
Drain up the buttermilk and add the prepared sauce. Mix well and leave it for 5 minutes. If you want to prepare it at a later time, you can put it back in the refrigerator.
Heat a pan with oil, add cumin and curry leaves, sauté till the cumin begins to splutter.
Transfer the onions and fry till golden.
Add the chicken and fry on a high heat for 2 to 3 mins. When you see the chicken turning white, cover it with a lid and lower the heat and cook till the chicken turns tender. This barely takes 5 mins if you are using strips
Remove the lid and fry till the moisture evaporates and the sauce begins to cling to the chicken. The longer it is roasted, the sauce becomes more aromatic and tastier but the chicken tends to lose its tenderness. So take off from the heat when it is of your liking. Take care not to burn, garlic burns faster.
Serve garlic chicken hot or warm.