Seed Weed For Sushi

Land caviar from kochia seeds I almost didn’t believe my first bite of wild-made tonburi—a preparation that involves boiling and soaking kochia seeds to make what is referred to as “land caviar.” Quick and easy collection of Japanese recipes

Land caviar from kochia seeds

I almost didn’t believe my first bite of wild-made tonburi—a preparation that involves boiling and soaking kochia seeds to make what is referred to as “land caviar.” The green and black seeds swell to a gelatinous texture with a shiny finish, and the mouth feel is the simultaneously slippery and crunchy texture of caviar.

The flavor is quite nice too. Tonburi has been described as tasting of broccoli and artichoke, and can be seasoned to give it a caviar-like flavor. According to tonburi purveyor BienManger, it is a specialty of the Akita prefecture in Japan and an ingredient in Buddhist vegetarian Shojin-ryori cuisine. It is often served seasoned with smoked fish or blended into a mayonnaise.

Truly, this is a wonderful ingredient—and with a little know-how and effort, we can access it for free. That’s because kochia (Kochia scoparia syn. Bassia scoparia), a non-native and some say noxious weed, is very plentiful in regions west, and in localized areas around the world.

Kochia seeds, winnowed to remove the chaff. The seeds swell, so even if it looks like you didn’t get that much, you will get several times the amount by the time you’re finished.

Getting the Seeds

Kochia seeds can be collected from late summer well into fall. The plant is easy to spot at this time because it often turns bright red before drying out to brown. In cultivated varieties, the entire foliage can appear red, such as in the magnificent display of cultivated kochia spheres at Hitachi Seaside Park in Japan.

Green kochia flower heads, with densely clustered spikes and long, skinny leaves subtending. Wait until these turn brown and dry out before harvesting the seeds. Photo by Gregg Davis.

Kochia proliferates in Denver, where it can grow taller than my head, and in my backyard at 10,000 feet in Colorado’s South Park. It is a common weed, often found in nearly pure stands spanning miles and miles of agricultural field borders and roadsides.

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In maturity, kochia has the appearance of a rounded-out, many-branched tumbleweed. Unlike Russian thistle (Salsola kali), another tumbleweed often found growing nearby, kochia is not spiny or otherwise injurious. The dry seed spikes sport tiny, inconspicuous fruits that, upon inspection with a magnifying glass, look a bit like flowers or stars because they have five, somewhat pointed, papery wings surrounding them. Each of the many tiny stars clustered on each branch has a skinny leaf sticking out from its base, and each contains a flat, teardrop-shaped black seed.

Stripping kochia seeds from dry plants near an abandoned building. Kochia likes waste places with disturbed ground; the trick is finding a good patch that isn’t growing right along the road. Photo by Gregg Davis.

Kochia seeds and chaff can be stripped into a collecting container easily by running a gripped hand along the branches. The tips of the branches left behind are filament-like—soft, white, and fuzzy at the tips. Since kochia tends to cover large areas and is a prolific seed producer, a patient forager can gather a substantial amount of fruits and tiny seeds.

Making Tonburi

My method for making tonburi from the dried, wild-foraged seeds involves first dumping the material into a big bowl and rubbing it between my fingers for a while. This is easy to do while watching TV. The process loosens the chaff and seed coats from the seeds.

Dried seeds, leaves, and fuzzy seed head spikes, stripped from the dry plants.

Next, because kochia is an easily spread non-native species, I don’t use my normal blow-in-the-bowl method to separate the excess leaf material and dry fruit casings. Instead I sift out the smallest bits of chaff through a sieve (I use our spatter guard), then employ my better half’s tap-the-cookie-sheet method to separate the rest. (This involves spreading the material out at one end of the cookie sheet, tilting it slightly, and tapping from underneath or above so the seeds roll and bounce to the other end, leaving the chaff behind.) It’s an imperfect method because the chaff inadvertently slides down too, so every tenth tap or so you have slide all the material back to the upper end of the tray. But the seeds do collect at the base, and can be transferred to a bowl by the spoonful as each batch is completed. Some chaff is likely to remain in the mix, but does not detract too much from the final product.

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After winnowing, the next step is to boil the seeds until soft, which for me took about 10 minutes at 10,000 feet, and then plunge them right away into cold water and let them soak overnight. Next, it is good to give the wet seeds another thorough rubbing to loosen any remaining seed coats, which can then be decanted off with the water. Then, rinse and strain to produce the caviar-like, vegan tonburi.

The soaked seeds swelled to produce a vegan caviar many times the dry volume. The texture and crunch are similar to real caviar.

Invasive Species-Made, Vegan Caviar

I used to buy caviar when I lived in California. Since then it seems to have increased in price, or I have just become poorer. In any case, I never purchase it anymore.

Black caviar from wild-caught sturgeon is a no-no on the Seafood Watch list from Monterey Bay Aquarium. “All 26 wild sturgeon species around the world are depleted or near extinction,” they explain. “These fish grow slowly, mature late and can’t keep up with the high demand for caviar.” The group recommends opting for caviar farmed in the U.S. or Canada as a best choice.

The first time I made it, I stared at my invasive-species-made, vegan caviar in disbelief for a while. What would you make if a sudden bounty of almost-caviar landed in your lap?

Online searches produced some exciting ideas. I found an image of butter-poached Murray cod with baby radish, braised Japanese daikon, tonburi, and crystallized wakame; another of chilled oyster soba, champagne jelly, pickled cucumber, and tonburi. I drooled over lobster with fried ribbons of sweet potato, tonburi, and lobster sauce. And the list goes on.

Although many sites describe tonburi as a gourmet delicacy, one commenter noted that according to Japanese-language websites, the seeds “only became ‘food’ after people in modern Akita prefecture were on the verge of starvation.” Whether delicacy, starvation food, or sustainable substitute for a depleted resource, I don’t care. The swollen kochia seeds are simply fantastic.

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A roll with cooked fish, avocado, wild plants, and tonburi. Photo by Gregg Davis.

In the end I made a million sushi rolls, using a palette of ingredients both wild and cultivated, topping each with a gorgeous trickle of tonburi.

You Can Have This Much Fun Too

For me, collecting wild seeds is a meditative activity, as is the time spent winnowing and rubbing. The entire process feels quietly transformational—and all the more so with kochia seeds, which turn into such magical “land caviar.”

When the kochia turns red in fall and then dries to brown, I exhort you, go ahead and collect some seeds. Let them dry out fully; it takes but a minute to spread them on a tray. You don’t even have to use them right away. But I promise—if you are willing to one day take the idea to fruition, there is a pot of gold at the end of this kochia rainbow.

UPDATE 10.22.17: Some people have reported an uncomfortable sensation in the throat upon consumption. I suspect saponins in the seed coats could be responsible, but have not verified this. However, I added an extra rub-and-rinse after soaking to the procedure described above as a precaution. That said, as with any wild edible, try just a little your first time. I find that combining it with other ingredients reduces the effect.

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Hello! My name is Mai. I’m from Kyoto, Japan. These are some of the most popular recipes in Japan. They are healthy and easy to make. Most of them take 20 minutes or less to prepare. Itadakimasu! (Let’s eat!) Contact Mai

The Japanese word for sushi rolls is makizushi. And tuna rolls are called tekkamaki (tekka roughly translates to “red hot iron”, because of the tuna’s resemblance to one). Cucumber rolls are called kappamaki (kappa is a mythological Japanese creature whose favorite food is cucumber). These are the most common sushi rolls in Japan.