Heat oil in a skillet over medium heat.
Add the beef and cook until it is no longer pink, approximately 6 minutes. Remove the beef from the pan.
While the beef is cooking, whisk together soy sauce, cornstarch, brown sugar, ginger, garlic, chili paste, and red pepper flakes.
Add the broccoli to the skillet and sauté until tender, around 4 minutes. Add more oil if necessary to prevent the broccoli from burning.
Return the cooked beef to the pan and stir in the sauce.
Cook until the sauce has thickened, about three minutes.
Serve the dish with rice.