Cut pork tenderloin in half to fit in your Instant Pot (if needed) and cook evenly. Rub all-purpose seasoning over all sides of the pork.
Set Instant Pot to sauté mode by pushing the sauté button. Add olive oil. When the pot is ready, brown the pork tenderloin on all sides, about 5 minutes total. While the pork roast is searing, I prepare the potatoes.
Remove the pork roast and let rest on a plate. Add the broth to the pot and stir to deglaze the pan.
Press the cancel button. Add potatoes to the bottom of the pot and place the pork tenderloin on top. Twist on the Instant Pot lid, turn the pressure lever to seal (if needed), then press the high-pressure button and set for 5 minutes.
When pressure cooking is complete, do a natural release for 10 minutes (let the pot rest undisturbed), then perform a quick release (turn or twist pressure valve).
Transfer pork roast to a serving platter and cover loosely with foil.
For Mashed Potatoes:
Using a slotted spoon, add the potatoes to a large mixing bowl. Add milk, butter, and seasoning. Mash the potatoes with a potato masher or mixer. Cover with foil.
For the gravy:
Press the sauté button until it says HIGH. In a cup, mix the corn starch and cold water. Using a whisk, stir the mixture with the broth until smooth. Continue stirring until the gravy is thick and bubbly.
Serving
Slice tenderloin roast into 1" slices before serving. Drizzle gravy over. Add a sprig of rosemary to serving platter for garnish.
Notes
Recipe Variations:
Pork tenderloin Instant Pot variations are easy to incorporate into this dish. Here are a few examples:
The best potatoes for this recipe are Yukon, but if you don’t have them, you can use red or russet instead. The key is to cut them to all the same size so they cook evenly.
You can also use garlic seasoning to make a garlic pork tenderloin by adding minced garlic to the pot.
If you’d rather use a lighter version of a sauce, drizzle a balsamic reduction on top instead of the gravy. You can make this reduction yourself or buy a bottle at your local grocery store.
Storing Instructions:
Refrigerate the pork and the potatoes in an air-tight container for up to 3 days. Be sure to completely reheat the pork up to 145 degrees to kill any latent bacteria.
After cooking, you can freeze the pork by wrapping it in plastic wrap and then putting it into a freezer bag. Make sure to label the bag with what it is, the date, and any thawing or cooking directions you want to add.
You can also freeze the mashed potatoes, however, it's not a good idea to freeze the cooked vegetables if you plan to eat them as a side. They tend to get mushy after freezing and thawing.