Remove and discard stems from mushrooms. Coarsely chop caps. Set aside.
Combine chopped fish, cornstarch and salt in a bowl; mix well.
Heat fish stock in a saucepan. Add mushrooms, vinegar, ginger, sesame oil, pepper and salt to taste. Bring to a simmer. Add fish; cook until fish is opaque.
Gently add tofu and goji berries to the pan and cook until heated through. Increase heat, stir in cornstarch solution, and cook, stirring, until soup boils and thickens, about 1 minute. Ladle into individual bowls and garnish with chopped cilantro.
Chef Yan has remained an active international food ambassador throughout his career. He roams the world representing different commercial and social concerns to entertain and educate the public, sharing with them his unique humor and strong passion for Chinese cooking.