Pickled kombu is traditionally served with fatty foods, such as fish, to help cut through the richness and refresh the palate.
Reserved 4 in (10 cm) kombu, cut into 1/2 in (1 cm) pieces (see recipe for Basic Kombu Stock) 1/2 tsp (2 mL) whole pink peppercorns 1 in (2.5 cm) piece fresh ginger, peeled and thinly sliced 1 cup (250 mL) unseasoned rice vinegar 1 Tbsp (15 mL) mirin
Place kombu pieces, peppercorns, and ginger in small (approximately 300 mL) sterilized jar.
In small pot, bring mirin and rice vinegar to a boil, then pour into jar, covering ingredients.When cool, seal tightly with a lid.
Refrigerate for two days. Serve.
Will keep up to two months, refrigerated.
source: "Sea Vegetables", alive #334, August 2010