• Preheat oven to 210°C Fan Forced.

For the Flathead

• Using a sharp filleting knife, reverse butterfly the flathead by cutting along the back and carefully removing the backbone while keeping the head and wings attached.
• Remove the rib bones and any remaining pin bones so the fish opens flat while the skin remains intact.
• Reserve the backbone for the jus.
• Set the Flathead aside in the fridge.

For the Flathead Jus

• Dust the reserved flathead backbone lightly with milk powder and toss with olive oil.
• Arrange on a roasting tray with the carrot, celery, fennel, onion and garlic.
• Roast for 20 minutes, or until well caramelised.
• Transfer the roasted backbone and vegetables to a pot. Deglaze the roasting tray with the white wine, scraping up any browned bits, and add this to the pot along with the fish stock.
• Simmer gently for about 15 minutes, then strain through a fine sieve into a clean saucepan.
• Reduce the liquid until concentrated and slightly thickened.
• Season with shiro dashi, lemon juice, a pinch of sugar and salt to taste.
• Whisk in the cold butter cubes to finish the sauce.

For the Breadcrumb Stuffing

• Melt the butter in a small pan over medium heat.
• Add the shallot, garlic and bay leaves and cook gently until softened and fragrant. Remove from the heat and discard the bay leaves.
• Transfer the shallot and garlic mixture to a small food processor.
• Add the breadcrumbs, anchovies, capers, preserved lemon, fennel seeds, chilli flakes, lemon zest and parsley. Pulse briefly until combined but still slightly coarse.
• Season lightly with salt and pepper.
• Spread the breadcrumb mixture evenly along the centre of the butterflied fish.
• Roll the fish tightly from head to tail so the skin forms the exterior of the roulade. Tie at intervals with kitchen string to secure its shape.

For the Rolled Flathead

• Heat a large frying pan over medium-high heat with a thin layer of oil.
• Sear the skin, rotating carefully so the fish browns evenly on all sides.
• Allow the thicker belly section to stay in contact with the pan slightly longer than the tail so the fish cooks evenly.
• Remove the fish from the pan but keep it on the heat.

For the Brown Butter Fish Sauce Glaze

• Add the butter and fish sauce to the frypan and allow the butter to brown lightly.
• Pour the brown butter glaze over the fish.
• Transfer the fish to oven and roast until the internal temperature in the thickest part reaches 48–50°C.
• Remove from the oven and rest for 5 minutes.
• The fish will continue cooking and finish at about 52–54°C, keeping the flesh moist.

To Serve

• Remove the kitchen string from the Rolled Flathead and top with fresh fennel fronds.
• Spoon the Flathead Jus onto the plate.
• Finish with a squeeze of lemon.