  We study the role of long-range electron-electron interactions in a system of
two-dimensional anisotropic Dirac fermions, which naturally appear in
uniaxially strained graphene, graphene in external potentials, some strongly
anisotropic topological insulators, and engineered anisotropic graphene
structures. We find that while for small interactions and anisotropy the system
restores the conventional isotropic Dirac liquid behavior, strong enough
anisotropy can lead to the formation of a quasi-one dimensional electronic
phase with dominant charge order (anisotropic excitonic insulator).
