Put the miso, 1.5 litres water, soy sauce, ginger and shiitake in a large saucepan. Stir to mix in the miso, then bring to a very gentle simmer. Keep simmering for 5 mins.
Meanwhile, place the smoked tofu in a shallow bowl and pour over the liquid aminos. Turn the tofu slices over to make sure they are soaked well on both sides.
Bring a pan of salted water to the boil. Add the soba noodles, bring back to the boil and cook until just tender, about 5 mins.
Add the baby corn to the miso broth and cook for a further 4 mins.
Meanwhile, heat the oil in a non-stick frying pan over a high heat. Lift the tofu from its bowl, shaking off the excess liquid aminos and saving it. Gently place the tofu in the frying pan and cook for 2-3 mins on each side until browned. Add the reserved liquid aminos to the pan (it will bubble up) and reduce to a glaze. Remove from the heat.
As soon as the noodles are cooked, drain them in a colander and rinse under cold water, then divide between four serving bowls. Add the pak choi to the miso broth and remove from the heat.
Divide the pak choi, baby corn and beansprouts between the bowls. Ladleover the miso broth and add the tofu. Garnish with the chillies, spring onions and crispy seaweed. Sprinkle with sesame seeds, drizzle over the sesame oil and serve straightaway.