In a large skillet or wok, heat the olive oil over medium-high heat. Once hot, add the sliced chicken and season with salt, pepper, and chili flakes. Cook until the chicken is browned and cooked through, about 5-7 minutes. Remove from the skillet and set aside.
In the same skillet, add the sesame oil, followed by minced garlic and grated ginger. Sauté for about 30 seconds until fragrant.
Add the sliced zucchini, mushrooms, and red bell pepper to the skillet. Stir-fry the vegetables for about 4-5 minutes, or until they are tender but still crisp.
Return the cooked chicken to the skillet. Pour in the soy sauce and toss all the ingredients together, ensuring everything is well coated. Cook for an additional 2 minutes to meld the flavors.
Remove from heat and transfer to a serving dish. Garnish with sliced green onions and sesame seeds before serving.
Notes
Adjust chili flakes to taste for desired spiciness.