Rinse and dry salmon thoroughly. Place salmon on sheet pan and season with salt and black pepper, set aside.
In the bowl of a mini food processor, add garlic and ginger. Pulse until finely minced.
In a large saucepan over medium heat, add 2 tablespoons grapeseed oil. Sauté garlic and ginger until softened, about 3 minutes. Stir in shoyu, Sriracha, chicken stock, mirin, yuzu juice and sugar. Bring to a boil and simmer on medium-low until slightly reduced, about 7-8 minutes.
Meanwhile, cook soba noodles according to package instructions. Drain and set aside.
In a large skillet over medium-high heat, add 2 tablespoons grapeseed oil. When oil is hot but not smoking, place salmon skin side up. Sear on each side until crisp, about 4-5 minutes on each side. Flip salmon only once.
Serve salmon skin side up over bed of soba noodles. Spoon sauce over salmon and noodles. Garnish with scallions and black sesame seeds. Serve remaining sauce on the side if desired. Serves 4.
Approximate Nutrient Analysis per serving (based on 2 pounds of salmon and 8 ounces of dry soba and not including salt to taste):
850 calories, 44 g fat, 8 g saturated fat, 125 mg cholesterol, greater than 1400 mg sodium, 54 g carbohydrate, 0 g fiber, 6 g sugar, 59 g protein