Start by roughly chopping all the veg for your stock and adding it to a large pan with the sesame oil, along with the seasonings, nori and salt and pepper. Cook for 5 mins until softened.
Add the mirin and 4 pints of water and veg stock, bring that to a boil and let simmer for 20 mins. Longer you leave it the more flavour that comes out.
Whilst that's simmering in a wok add the crumbled tempeh and soy sauce, cook this until browned and slightly crispy then set aside.
Now in the wok add more oil and the carrot, spring onions and Pak choy, cook for a few minutes, then add splashes of water and a lid until the carrots are softened and cooked.
Drain the veggies from your stock, then add batons of fresh ginger and the udon noodles back to the stock pan until cooked. Then serve up your soup with the noodles and cooked veg and tempeh, top with some chilli oil and coriander and get stuck in.