PICKLED GINGER (about 1 quart)
1 pound ginger (2 large roots), peeled and very thinly sliced or shaved (the key to this is cutting the ginger as thin as possible – you might try using a vegetable peeler)
1-1/2 teaspoons salt
1-1/4 cups rice vinegar
½ cup sugar
½ cup mirin
1. Combine ginger and salt and pack it into a quart container.
2. Bring vinegar, sugar and mirin to a boil in a large saucepan over medium-high heat. Stir until the sugar dissolves.
3. Pour warm liquid over the ginger. Let cool, cover and refrigerate for at least 1 week (2 to 3 weeks is better) and up to two months.
from Irma S. Rombauer, The Joy of Cooking