Cut tofu into bite-sized pieces.

Slice cabbage into 3cm widths, peel and slice carrot into 5mm rounds, trim and separate shimeji mushrooms, and cut green onion diagonally into 1cm slices.

Heat all soup base ingredients except soy milk in a pot over medium heat. Once boiling, add prepared vegetables and tofu, cover, and simmer on low heat for 5 minutes.