You don't. You either burn the CUE/FLAC combination in a burner that can decode the FLAC data or you play it in something that understands what CUEs are (lots of players AFAIK).
A CUE/FLAC is very much like an audio CD. An audio CD is just linear PCM data with a CDA-formatted header that states where all the track boundaries are. In your case the audio data has been losslessly compressed into the FLAC and the CUE is the track information.
Converting to WAV only serves to undo the compression. You might need to do this to burn it to disk.
Splitting into separate tracks
If you want to split the main FLAC into separate tracks, you can use the tools from the
shntool package as suggested in this blog:
cuebreakpoints filename.cue | shntool split -o flac filename.flac
You can also specify another output format instead of FLAC (option
-o flac in the example).
(You'll need to install the commands first:
sudo apt-get install cuetools shntool)
Tagging FLAC CD images for use with players like foobar
FLAC also allows for embedding cuesheets via
metaflac and compatible taggers. Players like foobar2000 and it's Linux equivalents (DeaDBeeF and Guayadeque) can parse and play files with such metadata. Importing a properly tagged cuesheet (along with other metadata like pictures), will also import tags like individual tracknames, tracknumbers, artist and album tags.
Excerpt from metaflac manpage:
Import a cuesheet from a file. Use '-' for stdin. Only one
FLAC file may be specified. A seekpoint will be added for
each index point in the cuesheet to the SEEKTABLE unless
--no-cued-seekpoints is specified.
But this kind of file format is rather unknown and unsupported outside the "distributed CD backup community". Mostly due to the fact that you cannot rip CDs to images on Linux like EAC does on Windows. (With EAC doing something very odd in this case, as I later learned.)