Place the venison in a large dish, add the rosemary, olive oil and lemon zest and juice and rub in well. Leave to marinate at room temperature for 15 minutes. Marinating will make these tender cuts even more succulent and flavourful.
Meanwhile, place the couscous, saffron and stock cube in a heatproof bowl and add 350ml boiling water. Stir well and set aside for 5 minutes until the water is absorbed and the couscous is tender.
Remove the venison racks from the marinade then barbecue them over hot coals or under a preheated grill for 10–12 minutes on each side until the deer meat is crusty and well browned but still pink in the centre. Leave to rest for 5 minutes before carving into cutlets.
Stir the peppers and parsley into the couscous. Serve with the wild venison racks.