Place sliced beef, ginger, garlic, and oil into pot on the saute function. Cook until the meat is no longer pink. Turn pot off. Stir in soy sauce, broth, vinegar and brown sugar.
Close lid and set to pressure high for 5 minutes. Do a quick release and lift lid. Add frozen broccoli and set to saute again (with lid open). Stir slowly until broccoli is cooked.
If you want to thicken the sauce, whisk in a small dish 2 tbsp cornstarch dissolved into 1/4 c water. Then pour this in, let it bubble until thicker and then turn off and serve.