  We report enhanced interlayer tunneling with reduced linewidth at zero
interlayer bias in a twist-controlled double monolayer graphene heterostructure
in the quantum Hall regime, when the top ($\nu_{\mathrm{T}}$) and bottom
($\nu_{\mathrm{B}}$) layer filling factors are near $\nu_{\mathrm{T}}=\pm1/2,
\pm3/2$ and $\nu_{\mathrm{B}}=\pm1/2, \pm3/2$, and the total filling factor
$\nu = \pm1$ or $\pm3$. The zero-bias interlayer conductance peaks are stable
against variations of layer filling factor, and signal the emergence of
interlayer phase coherence. Our results highlight twist control as a key
attribute in revealing interlayer coherence using tunneling.
