Add the oil to a large pot over a medium-high heat. Add the mushrooms, scallions, ginger and garlic, (and bamboo shoots, if using). Cook and stir for 1-2 minutes to infuse the flavor.Add the broth, red pepper flakes, vinegar and coconut aminos (or soy sauce). Bring to a boil, then reduce the heat and allow to simmer for about 10 minutes or until the mushrooms are tender.Stir the soup in a circular motion in one direction, then drizzle in the eggs in a thin and steady stream (while you are continuing to stir the soup) to create egg ribbons. I personally like to give the soup a swirl, then I like to pour the beaten eggs in a steady stream through a slotted serving spoon to encourage nice separated ribbons.Give the soup a taste and add more red pepper flakes and/or rice vinegar, as needed to get your desired flavor. Stir in ground white pepper.Serve hot. Garnish the hot and sour soup with chopped scallions, cilantro and a drizzle of sesame oil.