Step 1

In a bowl, mix together sugar, mirin, soy sauce, ginger and green onions.

Step 2

Truss the pork belly with butchers twine, and put it in a freezer bag with the marinade. Remove the air through a vacuum sealer or the displacement method. Put the bag in the fridge, and let the pork marinade for 10 - 24 hours (optional, but recommended).

Step 3

Set sous vide machine to 74C/165F. Once the target temperature is reached, drop pork belly in the bath for 10 hours.

Step 4

Remove bag from bath, and immediately transfer bag to an ice bath to cool down the pork belly. Once cooled, take pork belly out and pat dry.

Step 5

Heat a large skillet on high and add oil. Sear for 60 seconds on each side. Remove from pan, cut off the twine and place on plate to rest.

Step 6

Slice the chashu into 1/4-inch slices. When ready to eat, sear both sides of the chashu on a hot pan for 1 minute a side, or until browned.