In a medium saucepan combine the chicken broth, mushrooms, bamboo shoots, sliced ginger, garlic, soy sauce and chili flakes; bring to a boil, reduce heat to low and simmer while you assemble the other ingredients.
Place the chicken strips in a bowl and toss with the sesame oil.
In another bowl stir together the cornstarch and vinegar; set aside.
Increase the broth heat to medium-high and return to a full boil; add in the coated chicken slices and return to a boil again, then drizzle in the egg while stirring slowly to create long strands of egg.
Stir in the vinegar/cornstarch mixture; simmer over medium heat stirring occasionally until the chicken is cooked through and the broth has thickened slightly (about 3-4 minutes).