Mid-infrared light emitting diodes based on the pentanary alloy GaInAsSbP have been engineered to provide a favourable band structure for the suppression of non-radiative Auger recombination which is dominant in narrow band gap III-V materials. Hydrostatic pressure measurements at room temperature and at 100 K were used to tune the band gap towards resonance with the spin-orbit band gap. Analysis of the resulting electroluminescence confirms that the non-radiative Auger recombination process involving the spin-orbit-split-off-band is suppressed under ambient conditions.