Set the Instant Pot to saute function and brown the onions and beef cubes in one tablespoon of oil.
When the beef has developed some nice brown bits, add the soy sauce and ½ cup water.
Set to high pressure for 35 minutes.
Manually release pressure.
Remove beef and set in a separate dish. Boil remaining sauce using the Instant Pot’s saute function until reduced and thickened.
Serve sauce and meat over rice (*can use microwaveable rice or make your own) or mashed potatoes.