Toss 200 grams soybean sprouts, 100 grams garlic chives, 1 teaspoon potato starch, ¼ teaspoon salt, and a pinch of white pepper together in a bowl to distribute evenly.
Heat a non-stick frying pan over high heat until hot. Add 1 tablespoon vegetable oil and swirl to coat the pan.
Add the beansprout mixture and stir-fry until everything has cooked through and any liquid in the pan has thickened.
Drizzle over 1 teaspoon toasted sesame oil and 11 teaspoon usukuchi soy sauce and toss to coat evenly.