Gari is the thinly sliced ginger marinated in sweet vinegar accompanying sushi. We eat it to refresh our palate after eating fish, Ginger also has a minor anti-microbial properties which is useful when eating raw seafood.
I've started adding the gari making in my sushi classes this week as it is now the fresh ginger season. (although you can get it almost year round now). The pink color is natural which comes from the pink tip. (some store bought gari may use artificial food coloring). It is interesting to see the ginger turn pink after marinating it for a while.
I'm Miyuki and I teach Japanese Home cooking at my home in Tokyo.