Dissolve vegetable stock in boiling water. Place couscous in a heatproof bowl and add stock. Cover and let sit for 5 minutes. Fluff with a fork to separate grains.
Add cous cous to a large salad bowl along with cucumber, tomatoes, red onion, chickpeas, olive oil, lemon juice, and salt. Mix until combined.
Combine yoghurt, lemon juice, garlic, and chopped mint in a small bowl. Season with salt and pepper.
Preheat your BBQ to medium-high.
Coat each side of the lamb cutlets with olive oil, salt, and pepper.
Grill lamb cutlets for approximately 4 minutes on each side to desired doneness. (internal temp of 58°C for medium-rare). Transfer to a plate and let rest for 5 minutes.
Add salad to bowls along with the lamb cutlets. Add a good amount of the yoghurt dressing to each and some fresh mint.