Preheat your sous vide water bath to your desired doneness level. Refer to the time and temperature chart below.
Use salt and pepper to season the pork tenderloin. Chop or slice your garlic and shallots, then distribute evenly together with half of the herbs and place in the bag. Place your meat in the bag and seal airtight.
Place your prepared bag (with the meat and herbs inside) into the water bath for the time recommended in the chart below.
Once it’s fully cooked, remove your meat from the container and bag. Check the internal temperature to make sure it’s 145ºF to be safe to consume.
Prepare your paper towels and carefully pat your pork tenderloin dry. Heat up your olive oil in a cast iron skillet on your stove, until the oil starts to lightly smoke.
Place your pork in the hot pan using a pair of tongs. Add your butter, and the other half of your herbs, garlic and shallot for extra flavor. Cook everything in the pan for about 30 seconds, tilting the pan every so often and using a spoon to baste your pork with the herb butter, simple sauce in the large skillet.
Flip the pork tenderloin to cook the opposite side.
Take your pork out of the skillet and place it on a rack on top of a tray lined with a baking sheet.
Reserve all the drippings left in the heavy skillet and pour it on top of your pork.
Let it rest for 2 minutes – then slice it up and serve.