An improved rendering process and system including the use of both a slurry evaporator and cooker. Renderable material is ground and mixed with oil to form a slurry which is then cooked under vacuum in an evaporator to remove some moisture. The resulting partially dewatered slurry is partially deoiled, and the solids residue resulting from deoiling is cooked in a cooker to remove additional moisture. The hot vapors generated by cooking the material in the cooker are used in the steam jacket of the evaporator. Preferably the dewatered solids residue from the cooker is further deoiled.