Preheat oven to 200C.
Peel potato and slice 2mm thick using a mandoline. Using a 6cm cookie cutter, cut out 16 rounds from slices. Place rounds in a bowl, add 2 tablespoons grape seed oil and toss to coat. Transfer to a baking paper lined tray then cover with another layer baking paper and another tray. Place in the oven to cook for 20 minutes. Remove from oven and set aside.
Place 1 teaspoon grape seed oil in a saucepan and set over medium heat. Add the reserved prawn heads and shells and fry until fragrant. Add wine and bring to a boil. Reduce heat to low and allow to simmer until reduced by 1/3. Remove from heat and strain the mixture into a clean bowl. Add gelatine and stir to combine. Place in fridge to cool until almost set. Transfer cold mixture to an iSi gun and charge with 2 charges. Set aside.
Place 1 teaspoon grape seed oil and 1 teaspoon butter in a frypan and set over medium heat. Add prawns, season and cook, about 2 minutes per side. Remove from frypan and slice each prawn in half.
To serve, place 3 potato rounds on each plate. Place a prawn half on 2 of the potatoes and add a little tomato and spring onion. Place the scallop slices on the other potato round and add a radish slice and some coriander.
Remove iSi gun from fridge. Shake vigorously and add a squirt of foam to the plate. Add another potato round and season with salt.

MasterChef

Potato Clams