Bring a large pot of water to a boil. Meanwhile, in a large bowl, combine the sesame oil, black soy sauce, balsamic, sugar, salt, and Chile Oil. Whisk to blend. Stir in half of the sliced scallions. Set aside in the refrigerator.
When the water boils, season with salt until the water tastes like seawater. Plunge the pasta in the boiling water and cook, 3 to 5 minutes, until al dente. Place a colander in the sink. Remove the pot from the heat and pour off most of the water into the colander, catching any pasta as the water pours out.
Remove the colander from the sink and fill the pot still containing the pasta with cold water. You want the pasta to cool quickly by being submerged in the cold water. This will assure a chewy texture.
Drain the pasta thoroughly in the colander, shaking it a few times to remove excess water covering the pasta. Spread a kitchen towel on a flat surface and turn the noodles onto the towel. Gently use a second towel to dry the noodles. Removing the excess moisture assures that the sauce will have its proper flavoring effect on the noodles. Any water from cooking the pasta dilutes the noodles and makes them taste more like water than anything else. Gingerly transfer them the bowl with the sauce. Use your hands to mix the pasta and the sauce, taking care that all of the pasta gets coated. Cover with plastic and refrigerate until ready to serve.
These noodles can marinate for a few hours or overnight before serving. Serve them cold, tossing them again in the sauce just before serving, and garnish with the remaining scallions.
Fresh Chili Oil:
Remove the stems from the chiles then place in a food processor and blend until they are completely broken down.
Use a rubber spatula and scrape into a medium sized saute pan. Add the oil and stir well. Set the pan over medium-low heat. Gently warm up the oil slowly so it draws out the color and flavor of the chiles. Stir well and season with salt. Once the oil is barely simmering, cook for 5 to 6 minutes. hut off heat and allow to cool. Store in an airtight container until ready to use.