Bring the vegetable stock and 2 cups water to a simmer in a large saucepan. Stir in the tofu, bean paste and ginger until well incorporated and bring to a gentle simmer.
Add the bok choy and fish fillets and cook until the fish is opaque and the bok choy is crisp-tender and bright green, 3 to 4 minutes. Season with white pepper and serve garnished with a generous sprinkling of the cilantro and a few Cordycep mushrooms, if using.
