Fill the kettle with around 2 litres of water and boil. In a measuring jug pour one litre of water and add the miso and green teabag. Leave to infuse for 3-4 minutes.
Meanwhile, pour the remaining water over the soba noodles in a large pan and leave to soak with the lid on.
Remove the teabag from the infusion and stir the miso so it dissolves in the hot water.
Drain the noodles and return to the pan. Pour the miso and green tea infusion over the noodles. Submerge the shiitake mushrooms and Quorn pieces / vegetarian protein chunks in the noodle broth and switch on the heat to bring back to a simmer.
When hot, ladle portions into wide bowls and scatter over the spring onion, red chilli and coriander leaves. Serve immediately.
Notes
If you can't get fresh shiitake mushrooms, you can use dried ones but bear in mind these will weigh far less when dehydrated.