Marinate the skirt steak with cornstarch, baking soda, oyster sauce, soy sauce, oil, minced garlic, and ginger for 15 minutes.
Make the sauce by combining chicken broth, soy sauce, oyster sauce, sesame oil, and brown sugar.
Heat 1 tablespoon of oil in a large pan and cook the marinated beef for 5 minutes until fully cooked.
Remove the beef from the pan, add more oil, and cook the broccoli and minced garlic for 3 minutes until softened.
Pour the sauce into the pan and bring to a simmer.
Make a cornstarch slurry with cornstarch and water, then add it to the sauce and simmer for 2 minutes until thickened.
Add the beef back to the pan and simmer for 2 more minutes.
Serve the beef and broccoli over white rice, garnished with sliced green onion and sesame seeds.