Preheat sous vide precision cooker to 150º Fahrenheit.
Season chicken with salt and pepper on both sides.
Place chicken breasts in a Ziptop or food saver bag along with olive oil and/or other seasonings in the bag.
Vacuum seal or use the water displacement method to force out the air in the bag as you lower it into the water bath.
Cook for 1 -4 hours. (see notes)
After cook time, remove the bag from the bath and discard the purge and the bag.
Remove chicken breasts and pat very dry with paper towels.
Heat a cast-iron skillet over high heat until smoking hot.
Sear 1 minute per side or until nicely browned.