In a bowl add water and squeeze the lemon juice into the water.
Set up the mandolin cutter on a bowl. Ensure it is stable and does not easily move.
Slice the lotus roots as thin as possible, making sure that the slices are even all around. Let the slices fall into the bowl of water with lemon juice. This will prevent the slices from browning.
Once all the roots are sliced, drain the water and transfer the lotus root slices onto a tea towel and pat dry.
Heat the oil to 170ºC and test one lotus root to check it is hot enough. You will know that the oil is ready when the lotus root slice starts to bubble around the edges and starts to turn golden brown. Add a handful of lotus root slices each time and fry, turning them over for an even colour.
Deep fry all of the slices until golden brown. Remove from the oil with a slotted spoon and transfer onto a tea towel to remove excess oil.
Once all of the slices are done, transfer them into a bowl and sprinkle with salt and shichimi pepper and mix.
Transfer to an airtight container for storage in necessary.