Wash the sardines and gut or not (adds flavour)
Sprinkle a good layer of sea salt on foil and place sardines on top, then sprinkle more salt over, cover and refrigerate for at least 1 hour.
Remove sardines from fridge, brush off most of the salt and place on a fish grill tray
Mix oil and juice of ½ lime and brush over the fish
Grill on high heat on grill tray, about 4-5 minutes per side, baste with oil & lime juice.
Serve with remaining oil & lime juice, season with sea salt & rainbow peppercorn.