Wash strawberries and place in a paper towel-lined colander. Cover with another paper towel and place in the refrigerator for 4 hours.
Break your dry ice into small pieces, and toss with berries in a large bowl. Place into a container and cover with a towel. Place this in a cooler for 25 to 30 minutes. Remove berries and put into sealable bags and store in the freezer.
Recipe courtesy of Alton Brown