Thaw the calamari by placing the frozen boxes on the thawing rack in the storeroom. Transfer to the walk-in at the end of the shift.
The next day, remove the thawed calamari from the boxes, and place into a hotel pan. Rinse with cold water, then drain in a colander. Remove the fins from the tubes and the head cartledge from the legs.
Slice the tubes into 1/4″ rings. Combine with the tentacles, and mix with enough buttermilk to coat lightly. Portion into 6 oz. portions in plastic bags and store refrigerated.