Step 1

In a small saucepan, add mirin, sake, sugar. Turn on the heat to medium heat and whisk all the mixture.

Step 2

Then add soy sauce and bring it to a boil. Once boiling, reduce heat to the low heat/simmer and continue simmering for 10 minutes (or 20 minutes if you're making the full amount), or until the sauce slightly thickens. Toward the end of cooking, you will see more bubbles

Step 3

Remove from the heat. As it cools, the sauce will thicken more. You can store the sauce in an airtight jar and keep in the refrigerator for up to 3 months.

Step 4

Preheat the broiler* to medium (500ºF/260ºC) with a rack placed about 6" (15 cm) away from the top heating element (in the center of the oven) for 5 minutes. *Broiler setting: Low (450ºF/232ºC), Medium (500ºF/260ºC), and High (550ºF/288ºC). I usually use medium (6" away) or high (8" away). When broiling, you don't control the temperature in the oven; instead, you control the distance between the broiler and the surface of the food. It's similar to using hotter and cooler zones on your grill.

Step 5

Line a baking sheet with foil for easy cleaning (Brush/spray the foil with oil). Cut the unagi in half (or thirds, depending on the serving bowl size to fit the unagi fillet) and place it on the foil, skin side down. Broil it medium (500ºF/260ºC) until the surface is blistered a bit, about 5-7 minutes. No need to flip.

Step 6

Open the oven and brush the unagi with the sauce.

Step 7

Broil again for 30-60 seconds until you see bubbles on top of unagi.

Step 8

Preheat the oven to 425°F/218ºC with a rack placed in the middle and bake the unagi on parchment paper until the surface is blistered a bit, about 10-12 minutes. No need to flip.

Step 9

Wrap the unagi in foil (similar to this recipe) and reheat on low heat for 5-8 minutes. You won't get nice blisters/chars if you use this method.

Step 10

Serve rice in a bowl and pour or brush unagi Sauce on the rice. Serve unagi on top of rice and pour/brush more unagi sauce. Serve immediately. You can also sprinkle Japanese sansho pepper.

Step 11

You can keep the leftovers in an airtight container and store in the refrigerator for 3 days or in the freezer for 2 weeks.