  We construct Einstein-Podolsky-Rosen (EPR) steering signatures for the
nonlocality of the entangled superposition state described by
$\frac{1}{\sqrt{2}}\{|N\rangle|0\rangle+|0\rangle|N\rangle\}$, called the
two-mode NOON state. The signatures are a violation of an EPR steering
inequality based on an uncertainty relation. The violation confirms an EPR
steering between the two modes and involves certification of an inter-mode
correlation for number, as well as quadrature phase amplitude measurements. We
also explain how the signatures certify an $N$th order quantum coherence, so
the system (for larger $N$) can be signified to be in a superposition of states
distinct by a mesoscopic value of the two-mode quantum number difference.
Finally, we examine the limitations imposed for lossy scenarios, discussing how
experimental realisations may be possible for $N=2,3$.
