  Pulsars in relativistic binary systems have emerged as fantastic natural
laboratories for testing theories of gravity, the most prominent example being
the double pulsar, PSR J0737$-$3039. The HTRU-South Low Latitude pulsar survey
represents one of the most sensitive blind pulsar surveys taken of the southern
Galactic plane to date, and its primary aim has been the discovery of new
relativistic binary pulsars. Here we present our binary pulsar searching
strategy and report on the survey's flagship discovery, PSR J1757$-$1854. A
21.5-ms pulsar in a relativistic binary with an orbital period of 4.4 hours and
an eccentricity of 0.61, this double neutron star (DNS) system is the most
accelerated pulsar binary known, and probes a relativistic parameter space not
yet explored by previous pulsar binaries.
