Zest the limes, mix together the salt, sugar and lime zest.
Pin-bone the fish if necessary and the place it skin side down into a dish and cover with the salt mix. Allow to cure for 30 minutes.
Peel the beetroots, cook in boiling water for 5 minutes and allow to cool. Remove(keep the liquid) and slice thinly on a mandolin. Once sliced use a small pastry cutter to cut into even round discs do not throw away the trimmings.
Make a cure for the beetroot by blitzing together in a food processor the white wine vinegar, honey, caster sugar and garlic. Lay the beetroot disks out onto a tray and cover with the cure.
Peel the cucumbers, thinly slice into discs on a mandolin spread the discs out thinly on a tray, season with salt and freeze for 1 hour. Blanch the skin in boiling water for a few seconds and then refresh in cold water. Puree the blanched skin with the olive oil until smooth.
Peel the daikon and shave into long strips with a peeler, set aside in a mixing bowl. Bring the beetroot liquid and trimmings to the boil in a saucepan, pass through a sieve over the top of the daikon and mix well to stain the colour into the radish. Drain the liquid off after a minute or 2 once the daikon is pink.
Heat the oil to 180'C. Mix together the tempura flour with the soda water into a thin batter, dip the shiso into the batter and fry until golden.
Remove the fish from the cure and brush off any excess. Plate the dish by arranging 2 overlapping strips of the cured beetroot discs and then top with the sliced cucumber.
Cook the mackerel with a chef's blow torch (or under a hot grill) to brown the outside. It is cured so does not need cooking. Place the fish on top of the sliced cucumber. Place the tempura shiso leaf alongside and top with the stained daikon.
Drizzle the cucumber liquor around the plate and finish with a little coriander cress.
«Brining and curing are great ways of cooking, try using the cures here on different fish or seafood.»