Cut the flank steak into thin slices (or 1-inch in thickness. Any slices that may be longer than bite-size, you can choose to cut those down to size.
In a medium-sized bowl, place the steak. Over the steak, pour the cornstarch over every piece. With your hands or a large spoon, mix well until every piece of the steak is well coated.
In a medium bowl, mix together the soy sauce, beef broth, brown sugar, white wine vinegar, ginger, olive oil (1 tablespoon), garlic, ginger, and red pepper flakes.
Select the “saute” mode to the Instant Pot. Once it is hot, pour in enough olive oil to coat the bottom of the pot. If there isn’t enough oil, the cornstarch from the meat will stick to the pan, and the Instant Pot will not cook as it will “burn” the remnants on the bottom of the pan.
After the oil is hot, pour in the meat a little at a time. I suggest dividing the meat into three sections so as not to crowd the meat from browning. Brown each piece of meat. Once brown, remove from the Instant Pot and put to the side until all of your meat is browned.
Once all of your meat is browned, turn off “saute” mode. Return all of the meat to the pot, and pour the sauce over it. Put the lid on, and in the lock position. Close the sealing valve. Set the Instant Pot to High Pressure for 10 minutes. When the 10 minutes are done, do a quick pressure.
Stir in your green onions and sprinkle with sesame seeds. Pairs well over noodles, rice, or by itself!