In a small bowl, whisk together soy sauce, oyster sauce, rice vinegar, sesame oil, black pepper, and chicken broth. Set aside.
In another small bowl, mix cornstarch and water until smooth. Set aside.
Heat 1 tablespoon olive oil in a large skillet or wok over medium-high heat.
Add the sliced chicken breast and cook for 4-5 minutes until cooked through and lightly browned. Remove chicken from skillet and set aside.
Add the remaining 1 tablespoon olive oil to the skillet. Add minced garlic and ginger, sauté for 30 seconds until fragrant.
Add the sliced red bell pepper, yellow bell pepper, carrot, and broccoli florets to the skillet. Stir fry for 4-5 minutes until vegetables are crisp-tender.
Return the cooked chicken to the skillet with the vegetables.
Pour the prepared sauce over the chicken and vegetables. Stir to combine.
Add the cornstarch slurry to the skillet and stir continuously until the sauce thickens, about 1-2 minutes.
Remove from heat and garnish with sliced green onions and toasted sesame seeds.
Serve immediately with steamed rice or noodles if desired.