Dry skin overnight: Place pork belly on a plate. Pat skin dry with paper towels. Leave uncovered in fridge overnight to dry out the skin. (If you don't have time, pat the skin dry as best you can).

Preheat oven to 140°C/285°F (both fan and standard ovens).

Season flesh: Drizzle flesh side with 1 tsp oil. Sprinkle over 1/2 tsp salt, and all the pepper and Chinese five spice. Rub all over the flesh, including on the sides.

Foil boat: Place 2 pieces of foil on a work surface. Put the belly in middle of foil, skin side up. Fold the sides in to enclose the belly, forming an open box, pinching corners to seal tightly and make it as snug as possible. Place meat on a tray.

Season skin: Pat skin dry with paper towels. Rub with 1/2 tsp oil then sprinkle remaining 1/2 tsp salt evenly all over the skin surface, from edge to edge.

Slow roast 2 hours: Place in the oven and roast for 2 hours, tightening the foil around the pork after 1 hour (the pork will shrink). This protects the flesh from drying out.

Increase heat: Remove pork from oven, then increase heat to 240°C/465°F (all oven types).

Level pork: Remove pork from foil, discard fat and foil. Place pork on a rack set over a tray. Use scrunched up balls of foil stuffed under pork to prop it up so the skin surface is as level and horizontal as possible (see photos in post).

30 minutes blast! Place the pork back in the oven for 30 minutes, rotating after 15 minutes as needed, until the crackling is deep golden, puffy and crispy all over. If some patches are browning faster, protect with foil patches.

Rest 10 minutes: Remove pork from oven. Rest for 10 minutes before slicing.

Sauce - Mix the ingredients in a bowl then set aside. This will keep for 5 days in the fridge.

Chop pork - Cut the pork into 1 1/2 cm / 0.6" thick slices, then each slide into 1 1/2 cm / 0.6" chunks.

Split & spread - Split the roll in half down the side, keeping the lid attached. Smear the base with 1 1/2 tbsp of pate, then 1 1/2 tbsp of mayonnaise (on top of the pate)

Stuff - Pile about 1/3 cup pickled vegetables on the mayonnaise. Lay 2 slices of cucumber and 2 green onions against the lid. Pile pork on top. Drizzle pork with 1 tbsp of sauce. Stuff coriander/cilantro down the side, sprinkle with chilli then2 tablespoons of crispy shallots as you want (if using).

Serving - Eat immediately! Banh mi is definitely one of those foods best eaten freshly made!