Using a gallon size Ziploc bag, combine the steak, pear, brown sugar, soy sauce, minced garlic, ginger, and gochujang paste.
Remove the air and tightly seal the bag. Massage the bag to combine and cover the steak with the marinade.
Refrigerate the steak for at least two hours, up to 24 hours if time permits.
Put the Instant Pot on the saute mode. Add the vegetable oil and let it heat up (2-3 minutes). Place the meat in an even layer and saute for 2 minutes per side. Remove the meat and set aside. Continue sauteing until all of the meat is browned.
Place all of the meat back into the Instant Pot and set it to the meat setting for 20 minutes. Once it is done, mix in the green onions.
Garnish with the sesame seeds.