Into a small saucepan, add the butter and melt it over a low heat. Remove it from the heat once melted to cool slightly.

Meanwhile, add the vinegar and tepid water to a jug.

Into the bowl of a stand mixer, add the flour, cocoa powder and salt. Mix on a low speed with the paddle attachment.

Pour the melted butter in and mix on low speed.

Pour the remaining liquid into the stand mixer and mix on a low speed just until it pulls together into a rough dough with no more dry bits.

Lift the dough out onto a work surface and briefly knead it with your hands - about 30 seconds.

On to a large piece of acetate or parchment paper, draw a 20x25cm rectangle.

Lift the dough into the centre and fold the edges up to form a neat rectangle. Use a rolling pin to roll the dough to the edges of the rectangle and then chill the dough in the fridge for 3 hours or overnight.

Take a large sheet of acetate or parchment paper and draw a rectangular outline, 20x25cm. Place the butter into the centre. Wrap the excess parchment/acetate around the butter, folding the edges in to match the guides.

Use a rolling pin to roll the butter, pushing it to the edges and creating an even layer of butter across the rectangle of parchment. Place this in the fridge to chill for at least an hour, or overnight.

Prepare the dark chocolate cremeux as per the recipe. Pour the cremeux onto a tray, then chill this in the fridge for 3-4 hours.

Remove your butter from the fridge - it is ready to use when it reaches a temperature of 12C/54F.

Just before it is at temperature, remove your puff pastry dough from the fridge. We need this to be at around 4C/40F. Very lightly flour the dough, and roll it so that it is double the length of the butter block.

Place your butter into the centre of the dough so that the height of the dough and the butter match.

Fold the exposed sides of the dough into the centre so they meet in the middle.

Use your fingers to pinch the dough together to form a seam down the centre.

Using a sharp knife, carefully score the edges of the dough, where it is folded over the butter.

With this seam facing towards you, turn the dough 90 degrees so the seam is now horizontal to your body and give the dough a quick roll.

Turn the dough 90 degrees again so the seam is vertical in line with your body and begin to roll the dough.

Apply even pressure and roll the dough into a long, even rectangle, flouring very lightly if needed.

Once you are happy with the thickness and shape, dust off any excess flour with a brush.

Perform a single fold of the dough, where you take one-third of the dough and fold it up, then take the other third of dough and fold this over the top.

Wrap the dough and chill it in the fridge for 15 minutes.

Repeat this rolling and folding technique, chilling it in between each fold, performing a total of four single folds. Once you have finished the final fold, chill the dough for 1 hour in the fridge.

Add the fresh juice and agar agar to a small saucepan and bring it to a boil. Remove it from the heat and pour it onto a tray, and refrigerate for an hour.

Pre-heat the oven to 175C/345F Non-Fan Assisted.

Remove the chilled pastry and cut thin strips of dough, along the open seam side of the dough.

Lift the strips onto a lined baking tray, giving them enough space to spread.

Chill the strips of pastry on the tray in the fridge for 15 minutes, then place them into the oven and bake for 40-45 minutes.

Once baked, allow them to cool for 30 minutes.

Remove the chilled orange gel from the fridge and blend until it is a smooth gel. Add the gel into a piping bag and set it to one side.

Remove the cremeux from the fridge and whisk on a medium speed until it thickens to a more pipeable consistency.

Take your serving plate, and place one strip of puff pastry down.

Pipe two long lines of cremeux on the pastry.

Fill the centre with a line of orange gel.

Place a second layer of puff pastry on top and repeat the process.

Add a final layer of puff pastry, then dust lightly with cocoa powder and serve.