This question was asked on English Language & Usage and deconstructed food is a term I'd never heard before.
One answer is that it is simply the constituent parts of a dish laid out separately on a plate allowing the consumer to reconstruct the dish manually as they eat it.
A second answer was put forward suggesting that deconstruction is taking an existing dish (or sauce), examining it's constituent parts and recombining them (or some of them) in a different way to get a similar (or better) complete dish.
Searching on the internet shows a lot of the former (simple deconstruct), even for complex dishes that are normally prepared as a unit, like beef Wellington and lasagne.
It's harder to find references for the latter (deconstruct, examine, improve, reconstruct) but this is one for deconstructed onion soup, which is most definitely a single bowl of soup.
Edit : After reading TFDs comment I think I might have misunderstood the 'deconstruction' of the onion soup above, I think it means step-by-step instructions rather than deconstructed soup so after another search I did find this wonton soup that uses the term deconstructed in the sense I meant.
So my question is...
Does the term deconstructed food really mean separated constituents or does it mean improved or simplified by inspecting the constituents and recombining them differently?
...or does it mean both ?