Separate cabbage leaves into stems and leaves. Slice stems diagonally into 3cm widths and cut leaves into bite-sized pieces. Slice green onion diagonally into 1cm widths. Cut carrot into half lengthwise, then slice thinly into half-moon shapes. Trim and separate shimeji mushrooms.

Place oysters in a bowl with enough water to cover them. Wash gently, changing water 2-3 times. Pat dry with paper towels.

Add the seasonings (water, mirin, dashi powder) to a pot and heat over medium. Once boiling, dissolve miso and add soy milk.