01 - Toss the sliced beef with 1 tablespoon cornstarch until evenly coated.
02 - In a medium bowl, whisk together soy sauce, beef broth, brown sugar, sesame oil, garlic, ginger, rice vinegar, and red pepper flakes.
03 - Add the beef to the Instant Pot, then pour the sauce mixture over the beef. Stir to combine.
04 - Seal the Instant Pot lid and set the valve to Sealing. Cook on high pressure for 10 minutes.
05 - Quick release the pressure. Open the lid and add the broccoli florets.
06 - Reseal the lid and cook on high pressure for 1 additional minute. Quickly release the pressure again.
07 - In a small bowl, mix 2 tablespoons cornstarch with 2 tablespoons cold water to create a slurry.
08 - Stir the slurry into the beef and broccoli mixture. Turn on the Sauté mode and cook, stirring, for 2–3 minutes until the sauce thickens and broccoli is tender-crisp.
09 - Serve hot, garnished with sesame seeds and sliced green onions.