  In this letter we present a recursive method for computing one-loop off-shell
amplitudes in colored quantum field theories. First, we generalize the
perturbiner method by recasting the multiparticle currents as generators of
off-shell tree level amplitudes. After, by taking advantage of the underlying
color structure, we define a consistent sewing procedure to iteratively compute
the one-loop integrands. When gauge symmetries are involved, the whole
procedure is extended to multiparticle solutions involving ghosts, which can
then be accounted for in the full loop computation. Since the required input
here is equations of motion and gauge symmetry, our framework naturally extends
to one-loop computations in certain non-Lagrangian field theories.
