Place the Pork Tenderloin in a lidded container.
In a small bowl mix the honey, Dijon mustard, minced garlic, black pepper, and salt. Use a whisk to combine the pork marinade ingredients well.
Pour the honey mustard marinade over the pork, cover and marinate in the refrigerator for a couple of hours or overnight.
When ready to cook, heat the Instant Pot on the saute setting and melt the butter. Remove the pork tenderloin from the container saving the marinade.
Place the pork tenderloin into the Instant Pot and saute until browned on all sides. Remove the piece of pork from the instant pot and put the rack in. Place the pork tenderloin on the rack.
Add the reserved marinade to the Instant Pot along with the chicken stock. Place the lid on the Instant Pot and make sure the valve is set to the sealed position.
Press the manual button on the Instant pot and set the cooking time to 8 minutes.
Once the Instant Pot has beeped and the cooking time is over allow the Instant Pot to naturally release the steam for 10 minutes.
Carefully open the Instant Pot and remove the Pork tenderloin and place it on a serving platter. Allow meat to rest while making the gravy.
Turn the Instant Pot on the saute setting. Mix the water with the cornstarch in a small bowl. Once the liquids in the Instant Pot start to boil pour the cornstarch water into the Instant Pot. Use a whisk to mix the gravy until it thickens.
Turn the Instant Pot off and unplug. Carefully remove the gravy from the Instant Pot with a ladle and pour into a bowl or a gravy boat for serving. Slice the pork right before serving.