  We propose and validate a method of anti-neutrino energy reconstruction for
charged-current meson-less interactions on composite fully active targets
containing hydrogen (such as hydrocarbon scintillator), which is largely free
of the poorly understood nuclear effects that usually distort and bias attempts
to measure neutrino energy. The method is based on the precise event-by-event
measurement of the outgoing neutron kinetic energy and the subsequent
assessment of the momentum imbalance on the plane transverse to the incoming
anti-neutrino direction. For an anti-neutrino flux peaked at around 600 MeV
measured using a finely grained $2\times2\times2$ m$^3$ 3D scintillator tracker
the neutrino energy resolution is expected to be around 7%, compared to the 15%
expected using traditional neutrino energy reconstruction techniques. Analogous
results can be obtained for other detectors with similar characteristics.
