01 - Combine soy sauce, mirin, sesame oil, and sugar in a small bowl. Stir until sugar dissolves completely. Set aside for later use.
02 - Heat neutral oil in a large skillet or wok over medium-high heat until shimmering.
03 - Add sliced onions to the hot pan. Stir fry for 2 minutes until they begin to soften and turn translucent.
04 - Add minced garlic and ginger to the pan. Cook for 30 seconds until fragrant, stirring constantly to prevent burning.
05 - Add zucchini slices to the pan. Stir fry for 3–4 minutes until just tender but still crisp-tender.
06 - Pour the prepared sauce over the vegetables. Toss to coat evenly. Continue stir frying for 1–2 minutes until sauce slightly thickens and vegetables appear glossy.
07 - Remove from heat immediately. Garnish with sliced green onions and toasted sesame seeds.
08 - Serve immediately as a side dish or over steamed rice for a light vegetarian main.