In a small bowl, whisk together the chicken broth, soy sauce, rice vinegar, sesame oil, and cornstarch until smooth.
Heat olive oil in a large skillet or wok over medium-high heat.
Add the chicken cubes to the skillet and cook until browned and fully cooked, approximately 5 to 6 minutes.
Remove the chicken from the skillet and set aside.
Add the garlic and ginger to the remaining oil in the skillet and sauté for 30 seconds.
Add the broccoli florets and a splash of water, then cover with a lid to steam for 2 minutes until tender-crisp.
Return the chicken to the skillet and pour the sauce mixture over the ingredients.
Stir-fry for 1 to 2 minutes until the sauce has thickened and coated the chicken and broccoli.
Serve immediately.