Unadon (Unagi Don)

Bahan-bahan (4 porsi)

• 2 unagi (freshwater eel) fillets ((one fillet is roughly 5.6 oz or 160 g; defrosted))
• cooking spray ((or neutral-flavored oil, for broiling))
• ¼ cup mirin ((or substitute 3 parts sake or water + 1 part sugar))
• 1½ Tbsp sake ((or substitute Chinese rice wine or water))
• 2½ Tbsp sugar
• ¼ cup soy sauce ((use GF soy sauce for gluten free))
• Japanese sansho pepper ((optional))