  We present a new framework for computing low frequency transport properties
of strongly correlated, ergodic systems. Our main assumption is that, when a
thermalizing diffusive system is driven at frequency $\omega$, domains of size
$\xi \sim\sqrt{D/\omega}$ can be considered as internally thermal, but weakly
coupled with each other. We calculate the transport coefficients to lowest
order in the coupling, assuming incoherent transport between such domains. Our
framework naturally captures the sub-leading non analytic corrections to the
transport coefficients, known as hydrodynamic long time tails. In addition, it
allows us to obtain a generalized relation between charge and thermal transport
coefficients, in the spirit of the Wiedemann-Franz law. We verify our results,
which satisfy several non-trivial consistency checks, via exact diagonalization
studies on the one-dimensional extended Fermi-Hubbard model.
