Wash and dry the tomatoes.
Place on a freezer-safe tray and freeze until firm.
Place as many tomatoes into a zippered freezer bag (do not use a non-freezer bag).
Close the zipper almost to the end then choose 5 OR 6 below.
Place the bag into a bowl of water (being sure not to let any water enter into the bag) which will push out the air, then close the zipper completely. This is the best method.
Insert the straw into the bag and suck out the air from the bag and quickly finish closing the bag at the same time. This will remove more air which will help keep the tomatoes longer.
Place in the freezer for up to a year.