Place all of the ingredients in the Instant Pot (except for the broccoli if you want it to stay firm, the corn starch slurry and the sesame seeds) start with the sauce ingredients, and the shrimp follows. Cover with the lid, and make sure that the vent is in SEALING position.
Press on "manual" or "pressure cook", make sure that it's set at low pressure, and cook for 0 minutes. Let the Instant Pot come to pressure, then it will stop cooking and will beep. Quickly release the steam and carefully open the lid.
To thicken the sauce, press on "saute" and add the slurry to the pot. Mix it with the sauce, and the sauce will be thickened (it might take just 1 minute to do this, depending on how quick your sauce thickens). If it's not thick enough, then add one more cornstarch with water mixed together before adding to the pot. Mix in sriracha sauce if using.
After thickening the sauce, add fresh broccoli florets to the pot and cover with the lid. Allow the broccoli to "steam" for a couple of minutes and it will be slightly cooked but firm and crunchy.
Serve over rice, and garnish with sesame seeds.