Set sous vide machine to 58C/137F.
Salt and pepper rack of lamb to taste. Place rack of lamb in bag with 1 sprig of rosemary, 2 cloves of crushed garlic and olive oil. Remove the air through a vacuum sealer or the displacement method. Drop the bag in the bath for 2 hours.
While lamb is cooking, create the panko mixture. Add panko bread crumbs and sauté until golden brown, about 3 minutes. Remove from heat and add 2 Tbsp of chopped rosemary. Set aside and let cool.
Remove bag from bath. Take lamb out of the bag, pat dry and let rest for 5 minutes.
Smother the top of the rack of lamb with dijon mustard, then adhere the herbed Panko mixture.
Put coated rack of lamb in oven at 450F for 5 to 10 minutes. Take lamb out of the oven and let rest for 5 minutes. Slice the rack of lamb into individual chops and feast!