Method

• 1.
  Preheat the oven to 200°C. Cook potato in boiling water for 12-15 minutes until tender. Drain and return to pan. Mash until smooth, then add butter and yoghurt, and stir until smooth. Season and keep warm.
• 2.
  Heat 1 tbs oil in a pan over medium-high heat. Season the lamb and cook, turning, for 5 minutes or until browned. Transfer to a roasting pan with thyme and roast, turning every 4 minutes, for 12 minutes for medium-rare or until cooked to your liking. Rest, loosely covered with foil, for 5 minutes.
• 3.
  Meanwhile, chargrill cucumbers, cut-side down, over high heat for 2-3 minutes until charred. Transfer to a bowl. Drizzle with lemon juice and remaining 1 1/2 tbs oil.
• 4.
  Slice lamb, then serve with mash, cucumber and any resting juices.