Last Updated on June 3, 2023
Do you need a new variation of vegan “tuna” sushi? Then, try making my vegan Tomato “Katsuo” Nigiri Sushi. It is savory, slightly smoky with an accent of ginger and onion. You can definitely up your vegan sushi making with this recipe! What is katsuo? How is it different from vegan mock “tuna”? Let us find out!
Traditionally, sushi is not an everyday food. At occasional celebrations such as a rite of passage, seasonal events, and festivals to name a few, people get together to admire the moment and come together over a common interest food and of course sushi. That said, sushi is available nearly anywhere you turn in Japan at any time you need to calm your cravings. But still to this day, making my own sushi at home is something a bit more special.
Being Japanese, I have made vegan sushi in the past. Go figure. For me, what is really enjoyable about making vegan sushi is you can use your creativity and imagination to mock the look of the traditional ones. But I always play around with the flavoring to hold the natural taste and texture of the veggies. People often ask if they also taste like what they appear to be and the answer is, No!!
In case you do not know, high quality sushi never needs soy sauce! If you ever had good sushi (the traditional one with seafood), you know it is not about sauce and seasonings to flavor the seafood—It is rather focused on the quality and taste of seafood with a touch of condiments to enhance the flavor.
On the other hand, vegan sushi is quite different. Let us be honest, some veggies that you typically use for vegan sushi can lack in flavor if you do not properly season them. Although, you may be eating it with some kind of condiments, I think veggie sushi definitely deserves more than just soy sauce, wasabi, and spicy mayo.
Another thing is that the American interpretation of sushi seems to be “more is better.” It is typically drenched in weird sweet sauce and mayo-like sauce on top of overloaded unrecognizable things.
Now, my style of vegan sushi aims for:
- Minimal & Clean Look
- Complex yet Clean Taste
With this recipe of Tomato “Katsuo” Nigiri Sushi, it is very easy to achieve the above!
Katsuo [鰹] is a name of fish. In the US, it is more commonly known as bonito or bonito flakes to be particular. In Japan, katsuo is also eaten raw as sashimi or tataki-style [鰹のたたき] (cooked/torched slightly on the surface for the charred flavor) or sushi. It has a deep red color with a quite fishy and strong taste so it is typically served with ponzu sauce, scallions, and ginger to soften the edge.
My vegan version is made with tomato. Tomato can also be a good alternative to make vegan “tuna” but this time I intended to mock katsuo instead.
Even to this day, sushi rolls is the most popular sushi style in the U.S. For the Japanese, nigiri-zushi [握り寿司] (nigiri-style sushi) is the most common one and also considered the most traditional style when it comes to sushi. The word nigiri comes from the action verb nigiru [握る] which can be translated as grip, grasp, hold, and squeeze. I am not a sushi master so I can not speak about techniques to make it right. All I know is the rice for nigiri is always shaped into an oval using one hand, then the topping of your choice goes on it.
While nigiri is common in Japan, it is not something you make at home. Once you try it at home, you will immediately know, it is totally doable but not easy to make the right shape and to make it look unified and beautiful. But I can assure you that it is very fun and satisfying than making rolls!
Here is the list of ingredients to make this tasty nigiri!
- Sumeshi (Vinegared Sushi Rice)
- Roma Tomatoes
- Toasted Sesame Oil
- Smoked Sea Salt
- Onion (your choice of any kind. I used yellow onion)
- Soy Sauce (ponzu or tamari would be a good choice too)
In the next section, I can guide you through some of the ingredients above to help you with the process.
The Tips and Recipe Notes
Here is the breakdown on some key components and steps!
Sumeshi (Vinegared Sushi Rice)
You will not be able to make good sushi without having good sushi rice! Please see the post here for the recipe! It is definitely worth checking it out if you never made an authentic sushi rice. Or if you already know how to make good sushi rice, go with your own recipe.
Please note that the default servings of Tomato “Katsuo” Nigiri Sushi yields about 16 small nigiri sushi. That means, you approximately need a half of the amount of sushi rice that is in the Sumeshi recipe. You can use the other half for other toppings of your own! Something like sliced avocado will be a nice contrast in color and super easy to manage to use it up all 😉
I know it can be a lot of rice if you are making it for only one person but the recipe is what I consider “an easy-to-make amount.” That said, it can be possible to make smaller than what the recipe calls for as a default. You may adjust the amount accordingly.
The choice of tomatoes for this particular recipe or making sushi in general, Roma tomatoes (Italian plum tomatoes) would be perfect! It is firmer and less juicier than the other kinds so it will not fall apart easily. It has a nice red color and a bit sweet, a perfect candidate for mocking as vegan “tuna” or “katsuo (bonito).”
These are the brief steps of how-to (see the actual recipe for more details.)
- Make a cross-shaped slit at the both ends of tomatoes. Make sure not to go deep.
- Cook in soft boiling water until the skin starts peeling off.
- Transfer the half peeled (skin cracked) tomatoes to the ice bath.
- Gently remove the skin. It should come off easily.
- Quarter the tomatoes in lengthwise. Gently remove the seeds/core and trim off the button. It should look like sliced “bonito” or “tuna” if you will. Lay them flat in a single layer. Season with toasted sesame oil and sprinkle smoke sea salt on top. Set aside to marinate until the sushi rice is done.
Toasted Sesame Oil
The nuttiness of the toasted sesame oil adds a great aroma to the flesh of tomatoes. Extra virgin olive oil can be an interesting alternative, too. (←I have not tried it but sounds good to me.)
Smoked Sea Salt
This is one of the three key ingredients to make it taste like katsuo tatatki-style. I often use smoke sea salt to give a charred flavor without actually grilling or torching. The one I use is, alder smoke fine sea salt. Any smoke sea salt should work!
Sprinkle a few pinches and it should be enough to give a base flavor. Remember, you will be dipping in sauce later so do not over salt!
The second one of the three key ingredients is the ginger, grated one to be particular. katsuo tataki-style is often topped with grated ginger to offset the strong flavor of the fish. Of course, for the vegan version we do not have to worry about that at all. But again, it gives the same effect when you bite into it!
The last one of the three key ingredients is onion, thinly sliced one to be particular. Typically, scallions take place for this along with the ginger but onion works just as well! All you need is a tiny amount so it will not overpower everything else. You just want a hint of onion taste.
Sushi is typically served with wasabi. In this case, we use fresh ginger so wasabi is not necessary. Actually, it may conflict with the taste of ginger so I would not recommend it.
For the sauce, I used soy sauce. Ponzu is more common for katsuo tataki-style. Either one will work. For GF option, tamari is recommended. Our go-to soy sauce is always Ohsawa Organic Nama Shoyu from Gold Mine Natural Foods. They also carry tamari, and ponzu! If you eat organically and/or if you are into cooking Japanese food using real Japanese ingredients, you definitely want to check them out! 🙂
Be sure to check out our most popular vegan sushi recipes!
Tomato “Katsuo” Nigiri Sushi
Vinegared Sushi Rice
- 2 servings Sumeshi (Vinegared Sushi Rice) *
- 4 Roma (plum) tomatoes (about 1 pound / 454 g)
- 2 tsp toasted sesame oil
- A few pinches fine smoked sea salt
Toppings & Condiments
- 2-3 tbsp thinly sliced strips yellow onion (or red onion)
- 2- inch ginger knob peeled and grated
- Soy sauce (ponzu or tamari as an option)
- Make the Sumeshi (vinegared sushi rice) according to my recipe. Alternatively, you can make your own if you already have your go-to recipe of vinegared sushi rice.
- While rice is cooking, start preparing the tomato “katsuo.” Boil water in a medium sauce pan or pot.
- Meanwhile, make a cross-shaped slit at the both ends of tomatoes. Make sure not to go deep. Once the water is boiling, carefully drop the tomatoes into the boiling water. Reduce the heat to medium high. Cook until the skin starts peeling off. Prepare an ice bath.
- Transfer the partially peeled (skin cracked) tomatoes to the ice bath. Let it cool down to be able to handle with hands. Gently remove the skin. It should come off easily.
- Quarter the tomatoes in lengthwise. Gently remove the seeds/core and trim off the button. It should look like sliced “bonito” or “tuna.” Lay them flat in a single layer on a large plate or something similar. Season with toasted sesame oil and sprinkle smoke sea salt on top. Set aside to marinate until the sushi rice is done.
- Once the sushi rice is ready (it should be cooled down to the body temperature), start assembling. Damp your hands and grab a small amount of rice in one hand. Squeeze gently to form a small oval shape. Then use the other hand to place the seasoned tomato “katsuo” on top. Repeat the process
- To serve, top it with a few strips of onion and small amount of grated ginger along with soy sauce on the side.
- My Sumeshi (vinegared sushi rice) recipe is 2-3 servings by default which makes about small 30 nigiris. You will need about a half of the sushi rice to make this Tomato “Katsuo” Nigiri Sushi recipe which should make about 16 nigiris by default.