Bring salted water to a boil in a large saucepan, add the buckwheat noodles (soba) and boil for 8 to10 minutes. Drain.
Meanwhile, in a frying pan over high heat, put the sesame oil, bok choy and crushed garlic and cookfor about 3 minutes. Season with salt and pepper.
Prepare the sauce by whisking all the ingredients together in a bowl until the colour is uniform.
Add the noodles to the sauce and mix well. Place the shredded chicken and bok choy on top. Sprinklewith the chopped green onion, sesame seeds and chili pepper to taste.