Combine the dry spices, salt, pepper, garlic and oil. Make a few incisions in the brisket then rub all over with the marinade. Leave overnight for best results, however it is ok to cook straight away if needed.
Preheat an oven to 200?C. Place the brisket along with any extra marinade in a baking tray. Pour over the beef stock and cover the tray with baking paper followed by foil.
Place the brisket in the oven and cook for 30 minutes, then lower the temperature 140?C and cook for a further 3 hours, checking after 2 hours. The brisket is ready when the meat falls apart on prodding with some tongs. Allow the brisket to cool for 30 minutes then using a fork shred the beef, mixing some of the cooking liquid back in and adjust the seasoning to taste.
While the brisket is cooking, bring a medium saucepan of water to the boil, drain the soaking buckwheat then add to the boiling water. Cook for 3 minutes, drain and allow to cool. Stir through the sesame oil and seeds and set aside.
To make the pickled vegetables, combine the honey & apple cider vinegar in a glass bowl. Cut the cucumber, zucchini & carrot into matchsticks. Toss with the honey/vinegar mixture and leave for 15-20 minutes. Rinse, drain and squeeze the vegetables dry. Marinate in the vinegar mixture. Leave for at least 1 hour, then drain and store in the fridge.
Once the brisket has cooled and been shredded, heat a medium fry pan, add the oil and mushrooms, season with a little salt and cook until just wilted and starting to colour. Set aside. Add more oil to the pan and fry the eggs to your liking.
To serve, spoon some cooked buckwheat into the bowls, top with mushrooms, beef, pickled vegetables and a fried egg. Mix all the ingredients for the miso dressing, spoon over bowl and finish with the coriander and shallots.