  We study a solvable QCD--like toy theory, a generalization of the
Nambu--Jona-Lasinio model, which implements chiral symmetries of light quarks
and heavy quark symmetry. The chiral symmetric and chiral broken phases can be
dynamically tuned. This implies a parity doubled heavy--light meson system,
corresponding to a $(0^-,1^-)$ multiplet and a $(0^+,1^+)$ heavy spin
multiplet. Consequently the mass difference of the two multiplets is given by a
Goldberger--Treiman relation and $g_A$ is found to be small. The Isgur--Wise
function, $\xi(w)$, the decay constant, $f_B$, and other observables are
studied.
