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.