Step 1 Combine 2 teaspoons oil, lemon zest, 2 tablespoons lemon juice and seasoning in a shallow, non-metallic bowl. Roughly chop half the mint leaves and add to bowl. Add lamb, turning to coat with marinade. Cover and refrigerate for 1 hour.
Step 2 Finely shred remaining mint and place into a bowl. Add lettuce, tomatoes, cucumber, onion, olives, feta, remaining oil, garlic and remaining lemon juice. Season with black pepper and toss until well combined.
Step 3 Place a chargrill pan over medium-high heat (or heat a barbecue hotplate to medium-high). Once hot, add lamb and cook for 4 minutes each side for medium rare, or until cooked to your liking. Transfer to a plate, cover with foil and rest for 10 minutes. Thinly slice lamb and serve with salad, tzatziki and pita bread.