1. Combine the cure ingredients in a bowl until it's an even slurry.
2. Lay two long overlapping lengths of cling wrap on a tray or dish that will fit the trout lying flat. Press them together along the seam,then pour in half the cure,spreading it out along the length of the tray. Lay the trout on the cure,skin-side down,then pour the remaining cure over the top. Seal the parcel tightly with the overlapping cling wrap,ensuring the trout is evenly covered. Refrigerate for 24 hours,opening the parcel and turning the trout after 12 hours,then resealing.
3. Dehydrate the mandarin peel on a tray in the oven at 100C (80C fan-forced) for about 3 hours until brittle but still brightly coloured,not brown. Blitz in a spice grinder until fine,add the Sichuan pepper and white pepper and blitz again.
4. Once cured,remove the trout from the slurry (it will have firmed up and shed lots of water) and wipe clean with a damp cloth. Combine the olive and sesame oils and brush over the trout,then press on the mandarin dust. Wrap tightly in cling wrap and refrigerate for at least an hour before slicing (the trout will keep for about 10 days like this).
5. Combine the sesame mayonnaise ingredients well and refrigerate until needed. (Transferring it to a piping bag makes serving easier and more elegant,but it's not essential.)
6. Fry the wonton wrappers in about 4cm of oil at 180C for 2 minutes on each side,then drain on kitchen paper.
7. Slice the trout on an angle,then lay half a slice on a wonton triangle. Top with a dollop of mayonnaise,a celery leaf,some shallot and a couple of pearls of roe. Serve immediately with lime wedges. (If you let this sit for long,the wonton wrappers will soften.)
Tip:The base recipe for the cure is something you can adapt to your needs. Omit the Sichuan peppercorns and coriander seeds for a more classic result. Once the fish is cured,just brush it with dijon mustard and coat with chopped dill before wrapping and refrigerating.