Marinate the Chicken: Toss reserved sliced chicken with curry powder, annatto, garlic, and salt. Marinate at least 30 minutes or overnight.
Make the Curried Broth: Heat oil in a wok or 4 quart (4 L.) saucepan over high heat. Add marinated chicken; stir-fry for 3 minutes, until chicken begins to lose raw appearance. Add 6 to 8 cups of chicken broth; bring to a gentle simmer for 5 minutes (to cook chicken and develop flavor of broth). Taste; adjust seasoning with salt.