Step 1

Preheat the oven to 190°C and grease a baking tray. Season beef with salt flakes.

Step 2

Place oil and garlic in frypan over medium heat and cook for 2 minutes or until golden. Remove garlic and set aside. Add beef to frypan and cook 1-2 minutes each side until browned. Reduce to medium-low. Season with pepper. Add 20g butter and half the thyme, and return garlic to frypan. Cook 3-4 minutes, basting beef with butter mixture.

Step 3

Transfer beef to prepared tray and put butter mixture in a bowl and chill. Roast beef for 1 hour 45 minutes or until a meat thermometer reads 55°C for medium-rare. Rest 20 minutes loosely covered with foil.

Step 4

Return frypan to high heat and add chilled butter mixture and remaining 20g butter and thyme. Cook until butter foams, then add lemon juice. Pour over beef.

Step 5

Preheat a chargrill to high. Season lettuce and thread onto skewers. Cook cut-side down for 2 minutes or until grill marks appear. Turn and cook a further 1 minute or until grill marks appear. Drizzle with oil and scatter with herbs and cornichons.

Step 6

Thickly slice beef. Serve with lettuce and mustard.