Before you start, preheat oven to high grill. Preheat BBQ grill to high (if using).
Prep potatoes and garlic. Add potatoes to a medium pot and cover with hot tap water and a pinch of salt. Cook on high heat for about 25 minutes with the lid on, until tender. Drain and place on a lined oven tray.
Use a fork to crush potatoes. Mix garlic and butter together in a small bowl and drizzle over potatoes. Season with salt and grill in oven for about 10 minutes, until golden.
Meanwhile, prep oregano. Pat lamb dry and toss in a medium bowl with oregano. Season with salt and pepper.
Prep courgette and tomatoes. Toss in a medium bowl with vinegar and oil. Season to taste with salt and pepper.
When potatoes are grilling, heat oil in a medium fry-pan on medium-high heat. Cook lamb for about 2 minutes each side for medium (depending on thickness), or until cooked to your liking. Rest, covered, for 2-3 minutes. Alternatively, cook on the BBQ.
Prep feta and olives.
Serve potatoes and salad topped with feta. Serve with lamb and olives.