In a large pan, heat the vegetable oil over medium-high heat.
Add the chicken slices and season with a pinch of salt and pepper. Cook until the chicken is browned and cooked through, about 5-7 minutes. Remove the chicken from the pan and set aside.
In the same pan, add a bit more oil if needed, then add the broccoli florets. Stir-fry for about 3-4 minutes, or until the broccoli is bright green and slightly tender.
Add the ginger and garlic to the pan and sauté for about 1 minute, until fragrant.
Return the chicken to the pan. Add the soy sauce, oyster sauce, rice vinegar, sesame oil, sugar, and red pepper flakes. Stir well to combine.
Stir in the cornstarch mixture and cook for another 2-3 minutes, or until the sauce has thickened and the chicken and broccoli are well-coated.
Serve hot with rice or noodles.
