Cut meat against the grain into small bite-sized pieces. Sprinkle with kosher salt and pepper. See notes at the bottom.
Turn Instant Pot to "Sauté", add sesame oil and heat until hot.
Add meat in batches and brown. Remove from pot.
Add garlic and ginger and sauté for about 30 sec.
Add in soy sauce, brown sugar, red pepper flakes and rice wine vinegar and meat.
Cover with lid. Set pressure to high for 5 minutes on sealing. When finished, allow to natural release for 8 minutes, then release pressure.
In a small cup or bowl, add cornstarch. Add a few tablespoons of sauce from meat. Stir well, then add cornstarch mixture to Instant Pot. Stir. Set Instant Pot to "Sauté," and cook until boiling. Turn off pot.
Add broccoli, stir. Set Instant Pot to high pressure again (sealing) for 1 minute. This will take some time so if you're in a hurry and don't mind 2 bowls, you can always microwave or steam the broccoli separately but it's nice doing it in the Instant Pot so it's all in one pot. When finished, do quick release. Stir and serve with rice or cauliflower rice.