Remove bone and fat from arm roast. Then cut it into large chunks. Put into pressure cooker and sprinkle salt on top of meat.
Slice onion and put that on top and around meat.
Pour in all other ingredients in EXCEPT cornstarch, close lid. Seal steam valve and set to high pressure for 45 minutes.
Allow steam to naturally release for 15 minutes, then release rest.
Lift lid and remove meat and onions into a bowl. Set pot to saute. In a small bowl add 1/2 c of your hot broth from pot. Add cornstarch and whisk together until you create a smooth roux.
When liquid is bubbling pour your cornstarch mixture in. Stir continuously for about 3 minutes allowing this sauce to thicken.
Shred meat with forks in bowl. Pour this on top of meat so it is coated well and serve over rice!