Add water to the instant pot, then add trivet to the pot.
Make a small boat out of foil and place ham on top.
In a small bowl, mix together mustard, brown sugar, honey, nutmeg, and cinnamon. Brush ⅔ of the mixture on top and in between slices of ham. Place ham on top of the trivet.
Replace the lid on the instant pot and turn the valve to SEALING. Press MANUAL or PRESSURE COOK on HIGH PRESSURE for 4 minutes. Let the pressure manually release for 10 minutes, then turn the valve to VENTING and release the remaining pressure.
Remove the ham from the instant pot and pour remaining sauce over top. Serve warm.
Notes
Cook time: Technically, you will only set the timer for 4 minutes, but make sure that you account for the 10 minute natural release, and the time it takes the Instant Pot to pressurized. Even then, it takes about 35 minutes for a whole 3-4 pound ham to cook.Remember to use an instant-read thermometer, when checking for doneness, to ensure the ham cooks to an internal temperature between 135-150 degrees Fahrenheit. This guarantees a juicy, fully cooked ham that's safe for consumption.