Season the beef chuck roast with pepper. Cut beef against the grain, into thin strips. Set aside.
Pour the olive oil into the instant pot and turn on the sauté function. When the oil is hot, add the beef strips (in batches, if necessary, we don’t want to crowd it).
Let the beef to brown on all sides, this will take roughly 5-10 minutes.
While the beef is browning, prepare the sauce. In a medium sized bowl, add the soy sauce, oyster sauce, brown sugar, sesame oil, ginger, red pepper flakes, and garlic.
Stir this mixture together until combined. Set aside.
When the beef is browned, add the beef broth to the pot. Make sure to scrape up any bits of beef that are stuck to the bottom of the pot.
Next, add the sauce to the pot and stir well. Switch off the sauté function.
Place the lid on and seal the pot and set to cook on high pressure for 10 minutes. Once done, use the quick pressure release.
In a small bowl, mix the cornstarch and water together to create a slurry. Stir the slurry mixture into in the instant pot. Turn back on the sauté function and bring this mixture to a boil.
Next, add the broccoli to the pot.
Stir in, then place the lid on and allow this to boil for 3 minutes then turn off the sauté function. With the pot turned off, allow the mixture to sit for about 5 more minutes, or until the broccoli reaches your desired crispness.
Serve with rice, sliced green onions and sesame seeds if desired.