Heat 1 teaspoon of olive oil in a large nonstick skillet or wok over medium-high heat.
Season the chicken breast with garlic powder, onion powder, salt, and pepper. Add the chicken to the skillet and cook for 4-5 minutes until lightly browned and cooked through. Remove from the pan and set aside.
Add a teaspoon of olive oil to the skillet. Add the onions and green beans to the skillet and saute for about 5 minutes, until the vegetables are just cooked through.
To the same skillet, add the garlic and ginger and cook for 30 seconds until fragrant.
In a small bowl, whisk together the cornstarch and water until smooth. Then whisk in the soy sauce, oyster sauce, sesame oil, rice vinegar, and sweetener.
Return the chicken to the pan and pour the sauce over everything. Toss to coat.
Simmer for 2-3 minutes until the sauce thickens and evenly coats the chicken and vegetables.
Serve immediately, on its own or over cauliflower rice.