  We report results from the spectro-timing analysis of the atoll source 4U
1636$-$536 observed with NuSTAR and AstroSat during its hard spectral state. In
three observations of 207 ks total exposure, we identify 31 thermonuclear X-ray
bursts including five doublets and a triplet. Recurrence time as short as 3.8
minutes is seen in one of the doublets. To the best of our knowledge, this is
the shortest recurrence time known for this source. Our time-averaged
spectroscopy during the bursts indicate the presence of an additional powerlaw
or a blackbody component in a few cases, perhaps due to varying temperatures
during bursts or plausible deviation from ideal blackbody behavior, however, it
is difficult to probe this using the time-resolved spectroscopy owing to
limited statistics. Time-resolved bursts are well fit using an absorbed
blackbody model with temperatures varying between 1.7 and 2.2 keV. Burst
oscillations around 581 Hz are detected with 3$\sigma$ confidence during the
decay phase in two of the X-ray bursts. One of the burst oscillations is seen
at 582 Hz, a frequency observed during the 2001 superburst in this source.
