Instant Pot Pork Loin in Cranberry-Dijon Sauce

1 pound boneless pork loin roast
salt and pepper to taste
1 tablespoon butter
1 (14 ounce) can whole cranberry sauce
1/2 yellow onion, sliced
2 tablespoons Dijon mustard
2 tablespoons chopped fresh tarragon
1 packet dry onion soup mix
1 tablespoon cornstarch

Pat pork loin dry and season on all sides with salt and pepper.
Turn on a multi-functional pressure cooker and select Sauté function.
Add butter and let melt.
Add pork loin and cook on all sides until just a little bit of color shows, about 1 minute per side.
Turn off Sauté function and add cranberry sauce, sliced onion, Dijon mustard, tarragon, and dry onion mix.
Gently combine and spoon some of the sauce over the pork loin.
Close and lock the lid.
Select high pressure according to manufacturers' instructions; set timer for 9 minutes.
Allow 10 to 15 minutes for pressure to build.
Release pressure using the natural-release method according to manufacturer's instructions, about 10 minutes.
Check internal temperature of the pork loin; insert thermometer inserted into the center and should be 180 F.
Place on a cutting board to allow to rest for 8 to 10 minutes before cutting into thin slices.
While pork loin is resting, select Sauté function again and stir cornstarch into sauce.
Whisk until sauce thickens, 2 to 5 minutes.
Serve pork loin with cranberry-Dijon sauce.