Preheat the water bath using the Sous vide machine to 140F.
Season the meat with salt and pepper on all sides.
Place the meat in a vacuum bag with garlic, shallot, and thyme. Seal the bag with a vacuum sealer.
Place the bag with meat in the water bath, totally submerged in water and cook for at least 45 minutes.
Remove the pork tenderloin from the bag and discard the herbs.
Add butter to a non-stick skillet and sear the pork on all sides.
Slice and serve immediately.
Notes
TO STORE: Leftovers can be stored in the refrigerator, covered, for up to five days. TO FREEZE: Place the cooked and cooled pork in a shallow container. Store it in the freezer for up to 6 months. TO REHEAT: Microwave portions of the pork for 30-40 seconds or warm up in a non-stick skillet until hot.