  In this article we propose a new efficient strategy to construct exact
solutions of Einstein gravities with a minimally coupled self-interacting
scalar field. The strategy is to use the symmetry of the equations of motion
(EOMs) to give a proper ansatz for scalar field first, then derive the metric
and the corresponding scalar potential later. Using this strategy we give a
simple example of constructing exact circular solutions in three dimensional
gravities, these solutions contain the HMTZ black holes as a special case and
some other new solutions. We also talk about thermodynamics of these exact
solutions. This strategy also works for other metrics and in higher dimensional
spacetime if their EOMs admit a scalar invariance.
