Make the Chili Oil: In a stainless steel bowl, add the ginger, jalapeño, garlic, scallions, gochugaru, chili flakes, white sesame seeds, sugar, and salt. Add the grapeseed oil to a saucepan and heat over medium-high heat until it just begins to smoke. Turn off the heat and immediately pour the hot oil over the ingredients in the bowl. Mix thoroughly.
Make the Sesame Dressing: In a high-speed blender, combine all the dressing ingredients except the garlic and blend until smooth.
Prepare the Noodles: Cook the noodles in a large pot of salted boiling water until al dente. Drain. Rinse the noodles under cold water and drain well.
Assemble the Dish: Add the noodles to a large bowl and toss with the sesame dressing to coat. Top with the scallion greens and drizzle with chili oil.
