  We introduce a new foliation of AdS$_5$ black holes such that the conformal
boundary takes the form of a $4$-dimensional FLRW spacetime with scale factor
$a(t)$. The foliation employs Eddington-Finkelstein-like coordinates and is
applicable to a large class of AdS black holes, supported by matter fields or
not, considerably extending previous efforts in the literature. We argue that
the holographic dual picture of a CFT plasma on a FLRW background provides an
interesting prototype to study the nonequilibrium dynamics of expanding plasmas
and use holographic renormalization to extract the renormalized energy-momentum
tensor of the dual plasma. We illustrate the procedure for three black holes of
interest, namely AdS-Schwarzschild, AdS-Gauss-Bonnet, and
AdS-Reissner-Nordstr\"om. For the latter, as a by-product, we show that the
nonequilibrium dynamics of a CFT plasma subject to a quench in the chemical
potential (i.e., a time-dependent chemical potential) resembles a cosmological
evolution with the scale factor $a(t)$ being inversely related to the quench
profile.
