Pair fat layer and trim edges

Score remaining horizontally and vertically

Heavily season the duck breast with freshly cracked pepper and kosher salt

Vacuum seal duck breast (freeze if if you don't want to cook it the same day)

Sous vide at 130F for 3-5 hours (add one hour if frozen)

Preheat cast iron pan on high heat for 10-15 minutes

Remove duck breast from bags, pad dry thoroughly (also between scored fat layer)

Sear in hot cast iron pan, fat layer down first until golden brown and crisp. Flip and seat other side for 30-60 sec (can further enhance fat side seat with blow torch)