  We reexamine the vacuum structure of three-dimensional quantum chromodynamics
(QCD$_3$) with gauge group $SU(N)$, $N_f$ fundamental quark flavors, and a
level-$k$ Chern-Simons term. This analysis can be reliably carried out in the
large-$N$, fixed $N_f, k$ limit of the theory, up to certain assumptions that
we spell out explicitly. At leading order in the large-$N$ expansion we find
$N_f + 1$ distinct, exactly degenerate vacuum superselection sectors with
different patterns of flavor-symmetry breaking. The associated massless
Nambu-Goldstone bosons are generically accompanied by topological Chern-Simons
theories. This set of vacua contains many candidate phases previously proposed
for QCD$_3$. At subleading order in the large-$N$ expansion, the exact
degeneracy between the different superselection sectors is lifted, leading to a
multitude of metastable vacua. If we dial the quark masses, different
metastable vacua can become the true vacuum of the theory, leading to a
sequence of first-order phase transitions. This intricate large-$N$ dynamics
can be captured by the previously proposed bosonic dual theories for QCD$_3$,
provided these bosonic duals are furnished with a suitable scalar potential.
Interestingly, this potential must include terms beyond quartic order in the
scalar fields.
