Remove the skin from the pork belly in one intact piece; vacuum-seal the pork skin.

Sous vide the sealed pork skin at 72°C for 12 to 24 hours; cool it until safe to handle.

Blend the mixed fresh herbs, garlic, butter, and 1 teaspoon salt into a compound butter.

Spread the compound butter over the skinless pork belly; roll the pork into a tight cylinder.

Tie the pork roll tightly with kitchen twine; place it in the smoker with wood chips.

Smoke the pork roll at 140°C for 180 minutes; rest it with its rendered fat for 20 minutes.

Finely dice the mushrooms and onion; cook them in a frying pan until the duxelles is dry.

Whisk milk, 2 eggs, flour, and the remaining salt into a smooth batter; rest it for 10 minutes.

Cook the batter in a lightly oiled frying pan as thin crêpes; cool the crêpes completely.

Lay prosciutto over the cooled crêpes; spread the mushroom duxelles evenly over the prosciutto.

Place the smoked pork roll on the filled crêpes; wrap the crêpes and prosciutto tightly around it.

Roll the wrapped pork in puff pastry; seal the pastry edges with beaten egg.

Remove the sous vide pork skin from its bag; scrape off the excess fat.

Slice the pork skin into a lattice; brush the Wellington with beaten egg and place the lattice on top.

Bake the Wellington at 220°C for 30 to 35 minutes; rest it on a wire rack over a deep roasting tray.

Heat the neutral frying oil to 200°C; immediately ladle it over the pork-skin lattice to puff the crackling.

Slice the Porchetta Wellington into portions; serve each portion with gravy.

Lay the baked wellington on a rack over a deep tray and immediately pour over 200C oil to puff up the crust.

Slice a piece and serve with gravy.