Preheat oven to 200C. Heat deep fryer to 180C.
Place the salt, sugar, lime zest and lemongrass in a bowl and stir to combine. Lay a piece of plastic wrap on the bench, spoon half the salt/sugar mixture onto it. Add the trout fillet, cover with remaining salt/sugar mixture and wrap tightly. Place in the fridge to cure for 2 hours.⏱ 120 min
Meanwhile, to bake the potatoes, sprinkle rock salt on a tray, place potatoes on top and put in the oven to cook for 20 minutes until partially cooked. Remove from oven, peel and coarsely grate. Shape grated potato into rounds with a 4 1/2 cm cutter. Place rounds in deep fryer until golden, about 3 minutes. Remove from oil and set aside on a wire rack, to ensure they do not go soggy.⏱ 23 min
To pickle the daikon, place the rice wine vinegar, sugar, star anise, mustard seeds and ginger in a saucepan over medium heat and bring to a boil. Remove from heat, add the daikon and set aside.
Place the sesame seeds in a frypan and place over a very low heat. Cook, stirring, until seeds are toasted, about 15 minutes. Transfer to a small food processor add brown sugar and sea salt and process until a fine powder. Alternatively, use a mortar and pestle. Set aside.⏱ 15 min
To make the mayonnaise, place the egg, Dijon mustard and chardonnay vinegar in a food processor and process until combined. With the motor running, very slowly pour in the olive oil until the mixture is thick and creamy. Transfer mayonnaise to a bowl, add the reserved sesame seed powder and stir to combine. Season to taste and set aside.
Remove the cured trout from the fridge. Rinse, pat dry and sprinkle with green tea powder. Slice trout finely.
Remove daikon from pickling liquid.
To serve, place some cured trout onto a rosti. Top with mayonnaise and pickled daikon and garnish with micro coriander.