  We perform a canonical change of the field variables of light-cone gauge
massless QCD to obtain a lagrangian whose terms are proportional up to
polarisation factors to MHV amplitudes and continued off shell by the CSW
prescription. We solve for this transformation as a series expansion to all
orders in the new fields, and use this to prove that the resulting vertices are
indeed MHV vertices as claimed. We also demonstrate how this works explicitly
for the vertices with: two quarks and two gluons, four quarks, and a particular
helicity configuration of two quarks and three gluons. Finally, we generalise
the construction to massive QCD.
