If you are using dried lily buds, shiitake, and wood ear mushrooms are dried, soak them in hot water for 15 minutes to soften before preparation.
Prepare your vegetables. Trim off the hard ends of the lily buds and cut in half lengthwise. Slice all of the shiitake mushrooms, wood ear mushrooms, tofu, and bamboo shoots into strips.
In a large pot over medium heat, bring the water and vegetable bouillon to a boil. Add your lily buds, mushrooms, and bamboo shoots. Cook for 10 minutes.
In a small bowl, add the cornstarch and sugar. Slowly mix in the soy sauce, rice wine vinegar, and chili oil (if using) to create a smooth slurry. Stir the slurry into the soup until it well mixed. Return to a boil and cook until the cornstarch begins to thicken.
Add your tofu strips, white pepper, and salt to taste.
You must taste the soup! You are aiming for a balance of pepper (the "hot") and vinegar (the "sour"). If it tastes flat but spicy, you need more rice wine vinegar. If it tastes sharp but bland, you need more white pepper. If it's appropriately hot and soup but seems like it's "missing something," try adding a pinch of sugar.
Beat your eggs in a small bowl with a splash of water. Stir your soup in one direction for about a minute to create a vortex. Stop stirring. Slowly pour your eggs into the soup. Do not stir again for at least 2 minutes or your eggs will disintegrate into the soup!
If you're using bouillon to make the broth, I recommend making it strong. I typically use 2 quarts of water and 2 tbsp of vegetable bouillon for my Hot and Sour Soup.