On a cutting board, slice the flank steak into thin strips. Preheat the Instant Pot by selecting Sauté on Normal/Medium heat for 5 minutes. Add the avocado oil.
Once the pot is hot, add the steak and sear for 1-2 minutes. Stir in the minced garlic.
Pour in the beef broth, soy sauce, brown sugar, sesame oil, stirring until everything is well combined and the brown sugar dissolves.
Secure the lid and set the Instant Pot to Pressure Cook on High for 10 minutes. Once done, carefully quick release the pressure. When the valve drops, remove the lid.
In a small bowl, whisk together the water and the cornstarch until smooth.
Stir the cornstarch mixture into the beef until the sauce thickens and is smooth.
Select Sauté, add the broccoli, and stir. Close the lid and let the broccoli to cook for 3-5 minutes.