  The string+${}^3P_0$ model of spin-dependent hadronization is applied to the
fragmentation of a string stretched between a quark and an antiquark with
entangled spin states, assumed to be produced in the $e^+e^-$ annihilation
process. The model accounts systematically for the spin correlations in the
hadronization chain and is formulated as a recursive recipe suitable for the
implementation in a Monte Carlo event generator. The recipe is applied to the
production of two back-to-back pseudoscalar mesons produced in $e^+e^-$
annihilation, and it is shown to reproduce the form of the azimuthal
distribution of the hadrons as expected in QCD.
