In a bowl, whisk together miso, tahini and soy milk. Don't worry if miso and tahini are lumpy, they dissolve in soup at the end.
Boil 350 mil of water in a pot, add mushroom, leek, noodles, seasoning powder and vegetable flakes and cook for 4 minutes then add miso mixture to the pot and cook more 30 seconds to 1 minuite