In stock pot over medium heat, bring chicken broth to a simmer. Slowly stir in egg whites. Season to taste with salt and pepper. Heat through until whites are thoroughly cooked.
To serve, portion about 1/2 ounce shiitakes, 2 teaspoons green onions and 1 teaspoon cilantro into a soup bowl. Pour 1-1/2 cups eggs and broth into each bowl. Serve immediately.
Note: Do not let uncooked egg mixture remain at room temperature for longer than one hour (including preparation and service time).
To ensure food safety, eggs should be cooked until both the yolk and the white are firm. Consuming raw or undercooked eggs may increase your risk of foodborne illness, especially for those with certain medical conditions. For recipes that call for eggs that are raw or undercooked when the dish is served, use either pasteurized shell eggs that have been treated to destroy Salmonella, or use pasteurized egg products.