I say there are four categories:

• "standalones": anything that is only described as itself. Separation just results in smaller versions of itself.
• sandwiches: organized or layered arrangements of foods. Can typically be separated into it's composing parts.
• salads: tossed or jumbled arrangements of foods. Could be separated into its parts, albeit cumbersome.
• sauces: perfectly combined or blended arrangements of foods. Can no longer be separated into its composing parts, but differs from a standalone because it was still composed of other foods, and can still be identified or described as all of the parts.