Place lamb, half the oil, oregano and lemon zest in a large snap lock bag or shallow glass container. Season and set aside to marinate for 10 minutes.
Place potatoes in a microwave-safe container and cook on HIGH (100%) for 3-4 minutes or until nearly tender.
Heat a large lightly oiled char-grill pan or barbecue over medium-high heat. Cook potatoes for 2-3 minutes each side or until charred and tender. Set potatoes aside, keeping warm. Reheat same pan or barbecue over medium-high heat and cook lamb for 4-5 minutes each side, or until cooked to your liking. Rest on a plate loosely covered with foil for 5 minutes.
Meanwhile, combine remaining oil and lemon juice in a screw top jar, season and shake well to combine. In a large bowl, combine watermelon, tomato, cucumber, olives and feta cheese. Drizzle with dressing and toss to coat.
Serve lamb chops with watermelon salad, potatoes, mint leaves, lemon wedges and baby spinach (optional).
Lamb cutlets, loin chops or rump steaks would also work well in this recipe.
Cook extra chops, slice meat off the bone and add to a salad for a delicious next day lunch.
Use ricotta or goats cheese instead of feta; parsley or coriander instead of mint.