In a small saucepan over medium heat, warm vegetable oil. Add red pepper flakes (optional; I do NOT use this when making this dish for my kids) and cook, stirring, until the oil becomes slightly red and the pepper is fragrant. If you are not using the red pepper flakes, just add the garlic and ginger and cook until fragrant and soft, about 1 minute. Remove from heat.
In a small bowl, whisk together the sesame oil, soy sauce, brown sugar, balsamic vinegar, sugar and salt. Whisk in the garlic-ginger mixture. Set aside.
Cook noodles according to package directions. Buckwheat noodles only take 4-5 minutes to cook once the water is boiling. Drain and rinse under cold water. Transfer to a bowl. Add sauce and coat the noodles. I use plastic kitchen gloves for this part. LOVE the plastic kitchen gloves! Just before serving, place noodles in serving dish/bowl, and add toppings, sesame seeds and chives or scallions.