Heat a large skillet or wok over medium-high heat. Add the vegetable oil and allow it to heat for about 1 minute.
Add the sliced zucchini to the skillet and stir-fry for about 3-4 minutes, or until they start to become tender.
Sprinkle the garlic powder, onion powder, salt, and pepper over the zucchini. Stir well to combine.
Drizzle the soy sauce and sesame oil over the zucchini. Continue to stir-fry for an additional 2-3 minutes until the zucchini is cooked through but still crisp.
If desired, sprinkle sesame seeds on top and toss to combine. Remove from heat.
Garnish with chopped green onions before serving.