Slice the green onion into small pieces.

Heat salad oil in a pot over medium heat, add pork, and stir-fry until the color changes. Add the seasoning ingredients (sake, mirin, miso, dashi powder, water), mix well, and bring to a boil. Remove scum, cover, and simmer on low heat for 5–6 minutes to prepare the dipping sauce.

In a separate pot, boil plenty of water, add soba noodles, and cook according to package instructions. Drain and rinse with cold water to cool, then remove excess water.