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5 from 2 votes
Hero shot of Marinated Tuna Sashimi.
Marinated Sashimi Tuna
Prep Time
5 mins
Cook Time
10 mins
Minimum marinating time
8 hrs
Total Time
15 mins

This is quite a different way of serving sashimi. The sashimi is seared with boiling water first, then marinated in soy sauce flavour before slicing. With a white trim around each slice and semi-transparent dark red meat in the centre, Marinated Sashimi Tuna looks very attractive. Great for serving at gatherings, too.

Sashimi can be served as side, appetiser or even main. Just change the serving amount per person.

Total Time does not include the time to marinate.

Recipe Type: Appetiser, Main, Sides
Cuisine: Japanese
Keyword: sashimi, sashimi tuna, tuna, tuna marinade
Serves: 4 as side
Author: Yumiko
Ingredients (tbsp=15ml, cup=250ml)
  • 250g/0.6lb block of sashimi tuna (note 1)
  • A thin kitchen towel
  • Boiling water
  • Ice water in a large bowl
Tuna Marinade
  • 200ml/8.5oz water soaked with 5cm x 5cm/2" x 2" konbu (note 2)
  • 60ml/2oz soy sauce
  • 1 tsp sake
Garnish (optional)
  • 4 perilla leaves
  • finely chopped shallots/scallions
  1. Add water with konbu in a small pot/saucepan and bring it to a boil.
  2. Add soy sauce and sake to the pot. As soon as it starts boiling, turn the heat off and cool it down to at least room temperature, preferably even cooler. (note 3)

  3. Place the tuna block in the centre of a cutting board and cover the tuna with a kitchen towel.

  4. Place the cutting board with tuna on it in the sink, lifting one end higher to tilt the board.

  5. Pour boiling water over it gently to sear the surface of the tuna. Make sure that the side of the tuna is also seared. Do not sear too much. As soon as the surface becomes white, that is sufficient (see the photo in blog).
  6. Remove the kitchen towel, turn the tuna over and sear the surface in the same way.
  7. Transfer the tuna to the ice water to cool it down quickly.
  8. Pat the tuna dry with paper towel and place it in a container that just fits the tuna (note 4).

  9. Add the marinade to the container and ensure that the entire tuna block is submerged in the marinade (note 5). Cover the container with a lid/cling wrap and marinate for at least overnight up to 3 days (note 6) in the fridge.

  10. Remove the tuna block from the marinade and slice it into 7mm/¼" thick portions. Serve sliced tuna on perilla leaves by shifting each slice slightly to spread them and sprinkle chopped shallots over the sashimi if using.

Recipe Notes

1. Luckily, I could buy a neat rectangular shape of frozen sashimi tuna at the Japanese grocery store as you can see in the post. The size of the block was about 7cm x 14cm x 2.5cm/2¾” x 5½” x 1”. One block like this would be the easiest to handle.

But if your tuna comes in a different shape or in two smaller pieces, that’s quite alright, too. The important thing here is that the shape of the tuna block is suitable to make sliced sashimi.

2. Please refer to Varieties of Dashi Stock where the recipe for how to make Konbu Dashi is included.

3. If you want, you can make the marinade the day before.

4. You can also marinate tuna in a zip lock bag. But you need to turn the bag over occasionally while marinating so that the tuna is marinated evenly.

5. If your container is a bit too large and the tuna block cannot submerge in the marinade, place small shot glasses, bottles, baking beads, etc. around the tuna to increase the depth of the marinade. Of course, you can increase the amount of marinade as an alternative.

6. Searing the surface of the tuna prevents the marinade from penetrating into the flesh of the tuna too much. So, you can keep marinating for 2-3 days without making the tuna too salty.

7. Nutrition per serving as a side. I assumed 50% of marinating liquid would be consumed. Hence, the amount of sodium is very high. In reality, not much salt is absorbed into the tuna and sodium should be much less.

serving: 133g calories: 74kcal fat: 0.4g (1%) saturated fat: 0.1g (1%) trans fat: 0g polyunsaturated fat: 0.1g monounsaturated fat: 0.1g cholesterol: 24mg (8%) sodium: 481mg (20%) potassium: 313mg (9%) carbohydrates: 0.7g (9%) dietary fibre: 0.1g (0%) sugar: 0.1g protein: 16g vitamin a: 0.8% vitamin c: 0.1% calcium: 0.9 % iron: 3.7 %