Bring the bone broth and water to a rigorous boil over medium-high heat. Stir in cayenne, garlic, wakame, and tortellini. Allow to simmer for another 5–8 minutes, or until tortellini is cooked through. Season with salt and pepper to taste.
Use a ladle to spoon the soup into small crocks or heat-proof bowls. Drizzle with sesame oil and red pepper flakes. Serve immediately, you want this soup to be piping hot.