Mix the chicken pieces with the chili powder, salt and half of the yogurt. Marinate for 15 minutes. (Reserve the remainder of the yogurt for later use.)
In a large saucepan or wok, heat the oil over medium heat and stir-fry the onions until transparent before adding the minced ginger and garlic. Stir-fry until fragrant, about 5 minutes. Add the green chilies, c