Combine all the seasonings: salt, oregano, garlic powder, onion powder, rosemary, sage, and pepper in a small bowl.
Cut the pork tenderloin in 2-3 large pieces to make it easy to fit into the Instant Pot.
Pack the pork loins dry with a paper towel, then rub the seasoning mixture on the pork loin, making sure to cover each side.
Set the Instant Pot to Saute and add 2 tablespoons of olive oil for cooking.
Brown the seasoned pork tenderloin on all sides in hot oil. Set aside and turn-off the Instant Pot.
In a small mixing bowl or 2-cup measuring cup, add chicken broth, soy sauce, garlic, molasses, olive oil, and Dijon mustard. Whisk together until well combined.
Return the pork to the Instant Pot, add the sauce, and secure the lid with the vent set to "Sealing". Pressure cook on HIGH for 5 minutes (2lbs) or 7 minutes (3lbs). Allow for a Natural Release for 10 minutes, then manually release any remaining pressure.
Remove the lid and check the internal temperature of the pork. If it's below 145˚F, cover the Instant Pot and let it sit for a few minutes. Once done, take out the pork and let it rest for 5 to 8 minutes before you slice.
To make the gravy for the pork, remove the liquid from the Instant Pot; it should measure to about 2 cups. Add butter and set the Instant Pot to Saute. Gradually add the flour to thicken, creating a roux. Slowly whisk back in the sauce, followed by 1 cup of chicken broth (you should use about 3 cups of fluid between the sauce and the chicken broth). Cook until desired thickness.
Slice the pork and serve with gravy.