This vegetarian cold green tea soba dish can be served as a full meal, or as a perfect accompaniment to any grilled or roast meats or seafood. Fresh shiitakes are called for here, but re-hydrated dried shiitakes will do, offering up a deep flavor that one might characterize as "beefy."
I've also like to combine the shiitakes with wild mushrooms such as chanterelles, black trumpets, and oyster mushrooms. Any mushroom will do including white or brown cap mushrooms. Generally speaking, however, the more exotic or "wild" the mushroom, the more flavors the dish will have. Note: Shiitakes are easily found so increase the quantity of these in the event specialty types like chanterelles, black trumpets, or oyster mushrooms are not available.
Bring a large pot of water to a boil over high heat. Remove the ribbon from each portion of soba and add to the water. Cook until the noodles are tender yet firm, 3-5 minutes. Drain, shock under cold running water, and drain again. Transfer to a mixing bowl.
In a medium to large skillet, heat 1 tablespoon oil over high heat and stir-fry the garlic until fragrant and light golden, about 2 minutes. Add the shiitakes, oyster mushrooms, chanterelles, and black trumpets and stir-fry until just wilted, 1 to 2 minutes. Add to the noodles. In the same skillet add 1 tablespoon oil and stir-fry the spinach until just wilted, about 1 minute. Transfer to the noodles and toss to mix the ingredients well.
In a small bowl, whisk together the soy sauce, vinegar, mirin, wasabi, vegetable oil, and sesame oil until smooth. Add pepper to taste and pour over the noodles. Toss well and divide the noodles among large pasta bowls. Garnish with some pickled ginger and a sprinkle or two of sesame seeds.