Set the Instant Pot on the Saute setting. Add the olive oil.
Season the pork with salt and pepper on all sides. Add it to the Instant Pot and sear for about 1 minute on each side.
Add about 4 tablespoon of the brown sugar directly on the pork loin. On top of the brown sugar, sprinkle with paprika and chili powder.
In a small bowl, whisk together the remaining brown sugar, soy sauce, balsamic vinegar and stock. Pour the liquid mixture into the Instant Pot.
Close the lid and valve and set on HIGH pressure for 15 minutes, natural pressure release at the end.
Remove the meat from the pressure cooker. Tent with foil to keep warm. Turn the Instant Pot back to the sauté setting.
In a small bowl, whisk together 4TBSP of COLD water with the cornstarch to make a slurry. Whisk the slurry into the balsamic liquid. As it cooks, the cornstarch will thicken the glaze.
Slice the pork loin and serve hot with the balsamic vinegar glaze drizzled over the top.