In a large bowl, combine tofu, cabbage, scallions, ginger, garlic, soy sauce, sesame oil, and white pepper. Mix until well combined and slightly sticky.
Place 1 heaping teaspoon of filling in the center of each wrapper. Wet the edges with water, fold, and pleat to seal tightly.
Line a steamer basket with parchment or cabbage leaves. Arrange dumplings without touching. Steam over simmering water for 8–10 minutes.
While steaming, heat vegetable broth in a saucepan over medium-low heat. Stir in miso paste, ginger, soy sauce, sesame oil, garlic, and rice vinegar. Let simmer gently for 5–7 minutes.
Ladle hot broth into bowls and add dumplings. Top with scallions and chili oil if desired. Serve hot.