Heat up Instant Pot using Sauté More function. Wait until it says HOT (~8 mins). Add the oil to the pot then pat the tenderloin dry. Brown the pork tenderloin on all sides flipping after about 2 minutes.
While you are browning the tenderloin, combine the remaining ingredients in a small bowl.
Once the tenderloin is done browning, turn the instant pot off and carefully pour the prepared soy sauce mixture over the pork.
Place the lid on the instant pot and ensure that the steam valve is set to "sealing" Cook on high pressure for 2 minutes then allow a natural pressure release for 10-12 minutes.
After 10-12 minutes, carefully set the steam valve to "releasing" and allow any remaining steam to be released. The pork tenderloin should be at 145° F in it's thickest part. If it's not up to temp yet, return the lid and allow it to set for a few more minutes.
Once it is finished cooking, remove the pork tenderloin from the pot and set it aside to rest. Meanwhile, return the instant pot to high saute and allow the sauce to come to a boil, stirring frequently (more often if you are using brown sugar) until the sauce has thickened.
Pour the reduced sauce over the tenderloin, slice into medalions, and serve!
Be sure to read the post for tips and possible ingredient substitutions.The nutrition information provided is only an estimate and does not include any optional ingredients.