I was thinking that the individual portions (entree, veggie1, veggie2, dessert, etc.) would be produced under contract (or perhaps by Fleet owned companies and managed by local companies, much like how the contract to manage the Lake City Ammunition Plant is put up for bid every few years here in the States), and held to a commercial standard that would require the portion to be restaurant suitable.  The crew member would then draw whatever his ration allotment would be, and this would have a secondary benefit of allowing the ship's doctor to officially limit individual crew members to specific foods based on health needs.