Roughly chop the red cabbage. Use the outer leaves with a deeper colour.
Add water and cabbage to a pot and bring to the boil. Let it simmer for 5-10 mins bruising the cabbage with a wooden spoon.
Remove the cabbage and discard (compost).
Add the noodles to the purple water and turn over until they spread out in the pot and are fully submerged in liquid.
Turn the heat off and cover the pot for 10-15 minutes until the noodles have absorbed all the liquid.
Stir the noodles and strain off the excess liquid if there is any.
Place your noodles in a bowl and before serving roughly squeeze the lemon over the purple noodles and the acidity will change the colour to pink.