- 2 cups (packed) light brown sugar
- 2 cups mirin (sweet Japanese rice wine)
- 2 cups reduced-sodium soy sauce
- 1 cup chopped peeled fresh ginger (about one 4x1 inch piece)
- 2 tablespoons ground coriander
- 1/4 teaspoons whole black peppercorns
Bring sugar and 2 cups water to a boil in a medium heavy saucepan over medium-high heat, stirring until sugar dissolves. Boil for 2 minutes.
Reduce heat to medium; add mirin and next 4 ingredients. Simmer, stirring often, until sauce thickens slightly and has reduced to about 4 cups, 60-70 minutes.
Strain sauce through a fine-mesh sieve into a large heatproof pitcher. Divide among jars. Let cool. Screw on lids and chill. DO AHEAD Ambrosia sauce can be made 2 months ahead. Keep refrigerated.