Bringing out and highlighting the inherent flavors of ingredients is a fundamental principle of Japanese cuisine, including sushi. To use an analogy, when clouds cover a mountain, you cannot see the full landscape, but when they clear, a spectacular view unfolds before your eyes.
Sushi chefs, in particular, place great importance on bringing out the inherent flavors of seafood to the fullest, rather than layering flavors to the point that the seafood is transformed into something else. They value highlighting the unique taste of each individual ingredient over combining multiple types of seafood to create a new umami profile. Their philosophy is that this alone is sufficient to allow diners to appreciate the inherent deliciousness of the ingredients themselves.
On the other hand, plant-based nigiri sushi uses a variety of plant-based ingredients, such as vegetables, legumes, seaweed, mushrooms, and seeds, to develop its overall flavor. Even when combining multiple ingredients, it is possible to create a harmonious overall flavor while preserving the unique characteristics of each one.
As you can see, traditional seafood nigiri sushi and plant-based nigiri sushi take different approaches to bringing out the inherent deliciousness of their ingredients.
1. Differences in Ingredients
Many of the fish used in nigiri sushi are small fish that are often regarded as less desirable for cooking. Because these fish have many bones, are low in fat, and generally lack strong umami, chefs often avoid using them as culinary ingredients.
However, sushi allows us to transform these small fish—which are not particularly appealing when simmered or grilled—into delicious dishes. By removing the bones, applying precise knife techniques, and combining the fish with vinegared rice, sushi chefs can change the texture of the fish and the way its flavors are perceived. Their low fat content does not simply mean that they “lack fat”; rather, the fat they do contain conveys the vitality of young fish poised for growth, while offering a light and refreshing quality.
Nigiri sushi made with plant-based ingredients takes advantage of the diversity of plant-based materials, which differs from that of seafood. These ingredients include vegetables, legumes, mushrooms, seaweed, and grains, each with its own unique color, aroma, texture, moisture content, and fiber characteristics. Furthermore, even within the same plant, the shape and texture vary depending on the part used, such as the leaves, stems, roots, fruits, or seeds.
Unlike seafood nigiri sushi, plant-based nigiri sushi derives its distinctive character from the very differences in the shapes, structures, and textures of these diverse ingredients.
2. Differences in Flavor Based on Season and Origin
The flavor of seafood varies greatly depending on whether it is caught early in the season, at its peak, or late in the season, as well as on its region of origin. Fish caught early in the season offer a unique flavor characteristic of fish that are still growing, while fish caught at the peak of the season are appreciated for the rich flavor of their fat. Fish caught late in the season are savored for their deep flavor and the sense of nostalgia they evoke as the season draws to a close. As their fat content decreases slightly, the fish’s natural flavor becomes more pronounced, offering a special pleasure to those who enjoy this late-season delicacy while looking forward to the next season.
Furthermore, even within the same species, fat content and flavor vary depending on the region of origin. For example, sardines caught in Choshi differ in fat content and flavor from those caught in Osaka Bay. One of the defining features of sushi is that diners can actually taste and appreciate these differences.
Similarly, vegetables and mushrooms also have their own seasons, and even the same ingredient can vary in flavor and texture depending on where it is grown. By incorporating seasonal ingredients, plant-based nigiri sushi can fully express the distinctive character of each season.
3. Differences in Umami Components
Inosinic acid is a representative compound associated with the umami of fish. Although fish meat also contains glutamic acid, its concentration is generally lower than that of inosinic acid. When inosinic acid and glutamic acid are combined, they produce a synergistic umami effect. For this reason, fish is sometimes marinated with kombu to supplement its glutamic acid content. However, the presence of either compound in greater quantities does not necessarily mean that a dish will taste better.
In plant-based foods, on the other hand, glutamic acid is a key umami component. Additionally, mushrooms and certain other foods contain guanylic acid. The combination of these two different umami compounds—glutamic acid and guanylic acid—produces a synergistic umami effect.
In plant-based nigiri sushi, kombu and nori are sometimes used to enhance the umami of the plant-based ingredients. Kombu is rich in glutamic acid, while nori contains glutamic acid, along with small amounts of inosinic acid and guanylic acid. Combining these ingredients adds depth to the umami of plant-based ingredients.
However, isolating and examining the individual contributions of trace compounds in fish to its overall flavor is difficult. Therefore, the extent to which these compounds contribute to differences in flavor depending on the region of origin, or to seasonal variations between the beginning, peak, and end of a fishing season, has not yet been fully elucidated. These trace compounds are also believed to play an important role in the flavor of fish.
Furthermore, recent research has shown that lipids do more than simply contribute to a greasy mouthfeel. They can also enhance the perception of umami and saltiness, create a sense of fullness and a lingering aftertaste in the mouth, and thereby contribute to a dish’s overall richness. In other words, even lipids with almost no discernible taste or aroma can influence the overall deliciousness of a dish.
4. Why Aren’t Seafood Nigiri Sushi Layered?
In seafood nigiri sushi, it is uncommon to layer two or more different types of seafood on a single piece. This is because each type of seafood has its own subtle flavor, and the intention is to allow diners to appreciate these differences. When two ingredients are layered, the flavor of one can affect the other, making it difficult to distinguish the distinct flavors of each ingredient.
In sushi, the emphasis is not on transforming the fish into something with a different flavor, but rather on allowing diners to appreciate its natural flavor as clearly as possible. For this reason, using a single type of topping is also significant.
5. It’s Acceptable to Combine Ingredients in Plant-Based Nigiri Sushi
In plant-based nigiri sushi, there is value in combining two or more plant-based ingredients.
Plant-based ingredients each differ in sweetness, acidity, bitterness, aroma, texture, moisture content, and other characteristics. Therefore, combining multiple ingredients allows you to create flavors that are difficult to achieve with a single ingredient alone. For example, one ingredient can enhance umami, another can add acidity or aroma, and yet another can contribute a different texture. By combining these elements, you can create a well-balanced piece of nigiri sushi.
In other words, while bringing out the subtle flavors of each type of seafood is crucial in seafood nigiri sushi, combining multiple plant-based ingredients and making use of their individual characteristics to create a balanced flavor is also a key concept in plant-based nigiri sushi.
6. Pairing with Sake
When it comes to seafood nigiri sushi, sake that does not overpower the delicate flavors of the seafood is generally considered easier to pair with it than sake with a strong aroma.
On the other hand, since plant-based nigiri sushi contains virtually no inosinic acid of seafood origin, the umami components in sake can be considered part of the overall flavor profile. Sake contains amino acids and organic acids such as succinic acid, which contribute to its flavor. Therefore, it makes sense to actively consider pairing sake with plant-based nigiri sushi.
The pronounced ginjo aroma, which can sometimes overpower the delicate flavors of seafood nigiri sushi, does not necessarily pose the same problem with plant-based nigiri sushi. Since there is no need to preserve the delicate aroma of seafood, sake with a distinct ginjo aroma can also be a good pairing.
7. Making the Most of the Five Flavors, Five Cooking Methods, and Five Colors
Plant-based nigiri sushi offers greater opportunities to apply the Five Flavors, Five Cooking Methods, and Five Colors—the fundamental principles of Japanese cuisine—than traditional seafood nigiri sushi. The Five Flavors are sweet, sour, salty, bitter, and umami; the Five Cooking Methods are raw, simmered, grilled, steamed, and deep-fried; and the Five Colors are red, yellow, green, white, and black. In Japanese cuisine, great importance is placed on harmonizing flavors, cooking methods, colors, and seasonal elements by combining these principles.
In particular, the Five Colors can be incorporated by using plant-based ingredients in a variety of hues, creating a visually appealing color palette across the entire dish. Furthermore, the Five Flavors—sweet, sour, salty, bitter, and umami—can be balanced by combining different plant-based ingredients and seasonings.
8. Plant-Based Nigiri Sushi Designed with Nutritional Value in Mind
When preparing plant-based nigiri sushi, it is important to consider not only taste and appearance but also nutritional value.
In a diet based on plant-based foods, care must be taken when selecting and combining ingredients to ensure adequate intake of nutrients such as vitamin B12, vitamin D, iodine, long-chain omega-3 fatty acids, iron, zinc, and protein, which are often obtained from animal-based foods. In particular, it is difficult to obtain sufficient amounts of vitamin B12 consistently from plant-based foods alone, so supplements or fortified foods are sometimes used.
Therefore, this plant-based nigiri sushi combines a variety of plant-based ingredients, such as tofu, legumes, seaweed, mushrooms, leafy greens, and seeds, with careful consideration of the nutritional value of each ingredient. For nutrients such as iron and zinc, it is important to consider not only their content but also how different ingredients can be combined to enhance their absorption.
9. Using Seasoning Techniques from Japanese Cuisine
For plant-based nigiri sushi, we incorporate seasoning techniques commonly used in Japanese cuisine. These techniques serve not only to enhance flavor but also to add nutrients and umami components. Here are two representative examples:
Shiraae
Shiraae is a dish made by mixing mashed tofu with ground sesame seeds, white miso, vinegar, sugar, salt, light soy sauce, kombu dashi, and other ingredients, then tossing the mixture with vegetables. In plant-based nigiri sushi, we use only the shira-ae sauce, without mixing it with vegetables.
Tofu and sesame seeds provide nutrients such as protein and fat, while miso, soy sauce, and kombu contribute umami and depth of flavor. Although traditional shira-ae sometimes includes bonito dashi, plant-based nigiri sushi uses kombu dashi instead. While kombu dashi does not have the distinctive flavor of bonito dashi, it imparts a mild, delicate taste.
Dengaku Miso
Dengaku miso is a sweet-and-salty miso sauce used for miso dengaku, a dish in which tofu, konjac, or vegetables are coated with the sauce and grilled. In plant-based nigiri sushi, we use a dengaku miso made by combining Hatcho miso, sugar, mirin, sake, and kombu dashi.
Miso contains nutrients such as protein and also provides umami and richness resulting from fermentation. By adding the umami of kombu dashi, we can enhance the depth of flavor that might otherwise be lacking when using plant-based ingredients alone.
Summary
In plant-based nigiri sushi, seasoning and cooking methods are considered ingredients in their own right. The flavor of each piece is crafted not only through the ingredients themselves but also through the nutrients and umami components contributed by these methods.
In seafood nigiri sushi, adding a sauce or similar condiment to the topping generally places the dish in the category of “creative sushi.” This distinction highlights the virtue of a culinary tradition that takes pride in using as few unnecessary additions as possible.
Finally, plant-based nigiri sushi crafted by sushi chefs is not simply a matter of replacing seafood with plant-based ingredients. Sushi chefs do not approach it by using ganmodoki (tofu patties) instead of chicken or grilled eggplant instead of eel. Rather than recreating the appearance or flavor of fish or meat using plant-based ingredients, as seen in shojin ryori (Buddhist vegetarian cuisine), sushi chefs focus on making the most of each ingredient’s inherent qualities and bringing out its unique appeal.
At the same time, they seek to make up for the umami and nutrients that plant-based ingredients alone may lack through carefully selected ingredient combinations and cooking methods. The goal is to create nigiri sushi that everyone, regardless of whether they are vegetarian or vegan, can genuinely enjoy.