Cut the chicken and tofu into 1-inch cubes. Peel the carrots and cut into thick half-circle pieces. Chop onion into 1/2-inch pieces and cut cabbage into large segments.
In a saucepan over medium heat, combine all ingredients except the tofu and bring to a boil. Reduce heat and simmer gently for 10 minutes. Add tofu and miso, bring back to a boil briefly, then remove from heat and serve.