In a bowl, stir together the chicken stock, soy sauce, olive oil, fish sauce, mirin, ginger, oyster sauce, garlic, sugar and a pinch of white pepper. Transfer to a large skillet and bring to a simmer over high heat. Add the snow peas and scallion and cook, stirring, for 1 minute. Add the squid, tomatoes and cilantro and stir until the squid is just tender, about 2 minutes. Add the buckwheat noodles and toss until heated through. Season with salt and white pepper and transfer to 4 plates. Top the noodles with the nori strips and parsley and serve.