The gingerroot used to make amazu shoga should be as young and fresh as possible. The rhizome of fresh ginger contains pigment molecules and flavonoids called anthocyanins. When in contact with an acidic ingredient, like vinegar, the anthocyanin turns bright pink, giving the gingerroot a pinkish hue.

However, depending on the quality or freshness of the gingerroot, this will not always happen. Red food colouring is usually added to most types of commercially made amazu shoga to enhance the colour.

Instead of artificial colouring, you can add some rinsed purple perilla/shiso leaves (Perilla frutescens, in picture below right) in the pickle to colour the ginger.

young, fresh gingerroot (for quantity, see instructions below)
120 ml Japanese rice vinegar
50 ml water
1½ tbsp sugar

Choose a piece of gingerroot big enough to get 100 grams of peeled, salted and drained slices of gingerroot. Peel the gingerroot and place it on a deep plate. Sprinkle the root with salt, cover and let stand overnight. This will extract liquid out of the root.

On the next day, rinse and pat dry the gingerroot. Cut it in very thin slices and parboil the slices rapidly in boiling water. Drain the slices thoroughly and place in hot, sterilized jar.

Bring the rice vinegar, water and sugar to the boil in a small saucepan. Pour the boiling hot mixture over the ginger slices, seal the jar with sterilized lid and let cool. Ginger slices should turn beautifully pink in colour. Store the ginger in refrigerator and serve with sashimi.

Recipe source: adapted from a recipe in "The Book of Sushi" by Kinjiro Omae and Yuzuru Tachibana, rec.food.recipes posting, 1993.