Prepare the Broth: In a large pot, combine the vegetable broth, shiitake mushrooms, soy sauce, rice vinegar, sesame oil, garlic, and grated ginger. Bring it to a simmer over medium heat.
Add the Heat: Stir in the chili paste or sriracha to your preferred spice level, and let the broth simmer for 10 minutes to allow the flavors to meld.
Thicken the Soup: Mix cornstarch with cold water and slowly add it to the simmering broth. Stir constantly until the soup thickens to a silky texture.
Create Egg Ribbons: Gently drizzle the beaten eggs into the soup while stirring. This creates silky egg ribbons that add a rich texture.
Add the Bamboo Shoots and Protein (Optional): Stir in bamboo shoots and tofu (or chicken). Let it cook for another 2-3 minutes until heated through.
Serve & Garnish: Ladle the soup into bowls and garnish with sliced green onions and fresh cilantro. Serve immediately while hot.