Choose a container large enough to hold your food, with plenty of room for the water to circulate. Attach the Sansaire to the side of the container using the clamp and add water until the level is above the minimum fill line but below the maximum fill line. Remember that the water level will rise when you add your food.

Plug in and turn on your immersion circulator, turning the silver temperature ring above the display to 129°F. Wait until the target water temperature has been achieved before starting to cook.

Rub the rack of lamb with soy sauce to season. If available, seal using a vacuum sealer. Otherwise, place the rack of lamb into the Ziploc bag. With the top of the Ziploc bag open, carefully submerge the bag into the bottom of the water bath, without allowing any water into the bag itself. The pressure of the water circulating around the outside of the bag will push any air out of the bag and form a seal around the lamb. Using the side of the water container, carefully seal the bag and leave the lamb to cook in the water for 1 hour.

Meanwhile, combine the mint, sugar and butter in a small Ziploc bag. Remove the air from the bag following the same steps as above. Add the bag to the water bath with the lamb and cook for a minimum of 30 minutes, up to 60 minutes. Open the bag and strain out the mint leaves, reserving the melted butter. Refrigerate the butter until hardened.

To finish the lamb, add 2 inches frying oil to narrow pot with tall sides and heat to 375°F. Remove the lamb from the Ziploc bag and pat dry. Cut the rack of lamb into 2-rib segments and deep fry, working a few at a time, just until a golden crust forms on the outside, about 60 seconds.

To serve: Top lamb pieces with a dollop of reserved mint butter and sprinkle with lemon zest and flaky sea salt.