  Background: The advent of new dedicated experimental programs on hyperon
physics is rapidly boosting the field, and the possibility of synthetizing
multiple strange hypernuclei requires the addition of the strangeness degree of
freedom to the models dedicated to nuclear structure and nuclear matter studies
at low energy.
  Purpose: We want to settle the influence of strangeness on the nuclear
liquid-gas phase transition. Because of the large uncertainties concerning the
hyperon sector, we do not aim at a quantitative estimation of the phase diagram
but rather at a qualitative description of the phenomenology, as model
independent as possible.
  Method: We analyze the phase diagram of low density matter composed of
neutrons, protons and $\Lambda$ hyperons using a Relativistic Mean Field (RMF)
model. We largely explore the parameter space to pin down generic features of
the phase transition, and compare the results to ab-initio quantum Monte Carlo
calculations.
  Results: We show that the liquid-gas phase transition is only slightly
quenched by the addition of hyperons. Strangeness is seen to be an order
parameter of the phase transition, meaning that dilute strange matter is
expected to be unstable with respect to the formation of hyper-clusters.
  Conclusions: More quantitative results within the RMF model need improved
functionals at low density, possibly fitted to ab-initio calculations of
nuclear and $\Lambda$ matter.
