Heat the sesame oil in a wok or large frying pan and add the mushrooms and carrots. Quickly cook the veggies for a minute until just softened then add the chilli and ginger and cook for another 10 seconds.
Throw the choi sum or baby leaf spinach and spring onions into the wok and cook until the leaves are only just wilted. Remove from the pan and divide between 2 bowls.
Bring 700 ml water to the boil in a large pan. In a small bowl mix the miso with a couple of tablespoons of the water and then add the paste to the pan. Stir to combine and add a little more miso if needed. Divide the drained and diced tofu between the bowls and pour over the miso broth. Add tamari or soy sauce to taste and serve immediately.