Browning the turkey first adds depth of flavor to the stock. Slideshow: More Turkey Soup Recipes
Heat the oil in a medium saucepan over medium high heat until hot. Season the turkey with 1/4 teaspoon each salt and pepper, then sear the turkey, turning occasionally, until browned and cooked through, about 8 minutes. Transfer the turkey to a plate and let cool to warm, then shred the turkey.
Bring the stock, ginger, and 1 teaspoon salt and 1/2 teaspoon pepper to a boil in a the same saucepan. Stir together the soy and corn starch, then whisk into the broth and boil until the soup is slightly thickened, 1 to 2 minutes. Remove the saucepan from heat. Whisk together the eggs, sesame oil, and 1/2 teaspoon salt, then pour the eggs into the hot broth in a slow stream, whisking constantly to scatter the eggs as they cook. Stir in the chicken, then season the soup with salt to taste. Serve the soup topped with the cilantro and red pepper flakes.