Line a suitable number of 5 cm rings with cling film on the bottom. Place on a tray and place in the freezer. Dice the butter and set aside. Whisk the agar agar and 80 g of sugar together and whisk into the lemon juice and bring to the boil. Allow to boil for 2 minutes. Whisk together the remaining sugar and the eggs. Temper the hot lemon juice over the eggs. Return to the pan and cook slowly until boiling and it has reached a temperature of 85°C. Scale into the ring sat 30 g per ring and allow to set in the freezer.
Once the curd is frozen, remove the rings by gently warming them with a hot cloth or flashing them quickly with a blow torch. Store the tarts in the freezer or dip in white chocolate immediately.Melt together very gently, preferably in the hot cupboard or in the microwave. Blitz with a hand blender and pass through muslin.
Pierce each lemon tart with a fork, dip into the melted chocolate mixture, tap to remove any excess and place on a tray. Return to the freezer immediately.
Dice the butter and set aside. Whisk together the yuzu juice, sugar, yolks and whole eggs. Cook over a bain marie until a consistent temperature of 85°C has been reached. Soak the gelatine in cold water until very soft. Squeeze out the excess water and add the gelatine to the curd. Whisk to dissolve completely. Remove from the heat and whisk in the soft butter. Blitz with a hand blender and chill immediately.
Begin the sorbet syrup the day before you need to make the sorbet so it has time to chill properly: Combine the water, glucose, ProSorbet and sugar in a pan and bring to a boil. Allow to chill overnight.
Pour the yogurt into a large bowl and slowly whisk in the lemon juice. Continue to whisk gently as you add the sorbet syrup in a slow stream. Whisk continuously as though you were making mayonnaise. Transfer the mixture to paco jet containers and freeze.
Prepare the required amount of acetate sheets by cutting them in half so they are 30 cm x 40 cm. Prepare a similar amount of baking papers to the same size. Melt the cocoa butter colours gently, preferably in the hot cupboard or gently in the microwave. Shake well. Flick the colours carefully over the prepared acetates and allow to set. Temper the white chocolate and spread over the acetate sheets in thin layers. Allow to set until no longer tacky to the touch, cut out 1 cm x 6 cm rectangles. Cover each acetate with a sheet of baking parchment and place a tray on top to keep them flat. When you’ve finished all the sheets, allow to set completely for two to three hours in the chocolate fridge before removing the top tray to avoid breakages.
Mix all ingredients together until sandy. Pour onto a Silpat mat and spread evenly. Bake at 160°C until pale brown. Wait until completely cooled then blitz in ThermoMix.