  We show explicitly that supersymmetric $E_6$ Grand Unified Theory with a
Higgs sector consisting of $\{27+\bar{27}+351'+\bar{351'}+78\}$ fields provides
a realistic scenario for symmetry breaking and fermion mass generation. While
gauge symmetry breaking can be achieved without the $78$ field, its presence is
critical for a successful doublet-triplet mass splitting. The Yukawa sector of
the model consists of only two symmetric matrices describing all of quark,
lepton and neutrino masses and mixings. The fermion mass matrices are computed
at low energy and a fit to the second and third generation masses and mixings
is performed. We find a good numerical fit to the low-energy data. Thus, this
model, having $11$ superpotential parameters, alongside the two symmetric
Yukawa matrices, seems to be the best realistic candidate for a minimal
renormalizable supersymmetric $E_6$ unified theory.
