Preheat the sous vide (immersion circulator) waterbath to 125°F for Rare- Medium Rare. 133°F for Medium. 140°F Medium Well. 149°F for Well Done.
Portion clean, trimmed beef tenderloin into 3 inch tall portions. Tie with cotton butchers twine to hold the round medallion shape while cooking.
Season Beef with salt and pepper on all sides.
Place tenderloin and all other ingredients in a vacuum bag of your choice, remove most of the air from the bag.
Place sealed bag in waterbath, double checking for water leaks, and cook for 2 hours and 30 minutes.
Heat a cast iron saute pan or grill to a medium high heat. If doing so indoors on a stove, be sure to use a hood vent to not smoke out the house. Add a small amount of high heat oil to the pan, once heated just before searing.
Remove the tenderloin from the bag, careful to reserve the aromatics, butter and juices inside. Sear beef on two flat sides until deep golden brown and carmelized.
If searing in a sauté pan, add reserved juices and allow milk solids in the butter to brown. Baste meat by spooning buttery juices over the medallions until moistened.
Remove meat and crispy garlic cloves from the pan, cut twine to remove from meat, and let rest for 15 minutes covered in foil.
Slice, sprinkle with salt, and serve with your favorite seasonal vegetable sides and include the carmelized garlic for sweet punch of flavor.