Trim any excess sinew/fat from the topside and score the fat cap.

Season the meat with salt and pepper. It’s Danish lamb, so it doesn’t need to be marinated in garlic/thyme; the meat tastes good enough on its own.

Vacuum-seal the meat and place it in your sous vide/water bath.

Cook the meat for 3.5 hours at 56 degrees Celsius (133 degrees Fahrenheit). Since the meat is dry-aged, we always give it less time than regular "wet-aged" meat from the supermarket. I would probably cook wet-aged lamb topside for 4.5 hours at 56-58 degrees Celsius (133-136 degrees Fahrenheit).

Remove the meat from the vacuum bag and dry it thoroughly - ideally with a clean tea towel or paper towels.

Heat a pan to full heat and add either oil or ghee when it’s hot. If you’re using oil, you can add a bit of butter along with the meat.

Sear the meat for 30-45 seconds on each side and remove it from the pan. The meat doesn’t need to rest; it’s ready to serve immediately.

Slice it thinly and sprinkle with flaky salt.

Serve immediately.