This soup uses every part of the chicken.
1 tablespoon chicken fat or vegetable oil
11/2 tablespoons grated fresh ginger
11/2 teaspoons grated garlic
6 cups chicken stock
1½ teaspoons kosher salt
½ teaspoon ground black pepper
1 tablespoon soy sauce
1½ tablespoons cornstarch
1 tablespoon toasted sesame oil
2 cups baby spinach
1 cup shredded cooked chicken
3 scallions, thinly sliced
Hot sauce, optional
Melt the chicken fat or warm the oil in a 4-quart saucepan over low heat. Add the ginger and garlic and cook until they are just fragrant, about 1 minute. Add the chicken broth, salt and pepper. Increase the heat and bring the soup to a boil. Combine the soy sauce and cornstarch, then whisk the mixture into the broth. Simmer the broth until it thickens slightly, 1 to 2 minutes.
Remove the saucepan from the heat. Whisk the eggs, sesame oil and 1/2 teaspoon salt together. In a slow, steady stream, pour the egg mixture into the hot broth, whisking constantly to scatter the eggs into strands as they cook. Stir in the spinach and chicken. Serve the soup in warm bowls garnished with scallions and drizzle with hot sauce, if you are using.