Mackerel Pressed Sushi (Saba Oshizushi)

1. Gather all the ingredients. For the rice, please note that 1½ cups (300 g, 2 rice cooker cups) of uncooked Japanese short-grain rice yield 4⅓ cups (660 g) of cooked white rice.

To Prepare the Sushi Rice

1. Measure 1½ cups uncooked Japanese short-grain white rice. Rinse the rice under cold water by gently rubbing the rice with your fingertips in a circling motion. Submerge the rice in water and pour out the starchy water. Rinse and repeat until the water becomes clear.
2. Soak the rice in water for 20–30 minutes.
3. Drain the water completely and set aside for 10 minutes. If you don’t have time to wait, then shake off the excess water the best you can. Transfer the rice into the inner pot of your rice cooker.
4. Pour water up to the 2 cups line for Sushi Rice (or a little bit less than 2 cups for regular White Rice, if you don’t have the Sushi Rice option) and start cooking. If you do not have a rice cooker, prepare 360 ml water (we use less water than regular rice as you will season the rice after the rice is cooked) and follow my recipe for how to cook rice in the Instant Pot or in the pot over the stove.
5. Once the rice is done cooking, fluff with a rice scooper/paddle. Moisten a sushi oke/hangiri (a round, flat-bottom wooden tub) or a large bowl with water so the rice will not stick. Transfer the cooked rice into the sushi oke and spread out evenly so the rice will cool faster.
6. To the hot rice, add 4 Tbsp seasoned rice vinegar (sushi vinegar) or the homemade rice vinegar; I used Kikkoman® Seasoned Rice Vinegar. (To make homemade sushi vinegar, combine 4 Tbsp rice vinegar (unseasoned), 2 Tbsp sugar, and 1 tsp Diamond Crystal kosher salt in a microwave-safe bowl and heat for 1 minute, or until the sugar is dissolved. Let it cool, then add to the hot rice.) Add more or less to your liking. With a rice paddle, slice the rice at a 45-degree angle to separate the rice grains instead of mixing. Meantime, use a fan to cool the rice so it shines and doesn‘t get mushy.
7. Gently flip the rice in between slices. Repeat this process until the rice is cooled. Keep the rice covered with a damp towel (or paper towel until ready to use.

To Prepare the Mackerel

1. Open the package of 1 frozen marinated mackerel fillet (shime saba) that you have defrosted. Cut the slab in half lengthwise.
2. Butterfly the fillet from the long edge that you just cut. Please watch the video tutorial above to see how I do this. Repeat with the other half.
3. [Optional] Place the mackerel pieces on a ceramic plate and use a kitchen torch to lightly sear the skin for a nice charred flavor.

To Make the Pressed Sushi

1. Prepare a small bowl with water and add 1 Tbsp Kikkoman® Seasoned Rice Vinegar (or rice vinegar). Moisten your hands with this vinegar water so the rice won’t stick to them.
2. Assemble the oshibako (sushi press) mold with the bottom base and side so the top is open. Moisten it with the vinegar water so the rice won’t stick to it.
3. First, put the mackerel fillet at the bottom, skin side down. When the fillet is bigger than the box, cut off the excess and fill in all the voids if any.
4. Then add 6 shiso leaves on top of the mackerel.
5. Add the sushi rice from one side to the other. Using your fingers, fill the rice right into the corners and try to keep the amount of rice even all over.
6. Add more rice if necessary and fill the mold just right above the rim.
7. Place the top piece of the mold and use it to press down on the rice firmly.
8. Rotate the mold 180 degrees and press down again firmly with your body weight.
9. Flip the mold so the top piece is now at the bottom. Slide the sidewall of the mold down.
10. Remove the top piece. If the fish is stuck to the top piece, use a knife to detach. Push up the bottom piece through the sidewall.
11. The completed oshizushi is now on the bottom piece. Insert a knife to detach from the bottom piece.
12. Cut the oshizushi in half crosswise and cut each half into 3 pieces. Serve on a plate and garnish with pickled ginger. You can repeat for another piece of mackerel. Clean the mold and moisten before making the second batch. Alternatively, you can use plastic wrap to avoid cleaning every time.

What to do with leftover Sushi Rice?

1. You can make Temari Sushi or Hand Roll Sushi for a quick sushi fix. Or you can freeze the sushi rice up to 1 month.