"After minutes upon minutes of research online, I found out that it's bracken starch," Matthew Kirkley said of his ingredient. That is, it comes from the roots of the bracken fern, and is sometimes referred to as bracken starch—but it's most often used in Japan, where the plant is called warabi, hence the more common name, warabi starch. Warabi mochi is the most popular application: the starch is cooked with water and sugar, formed into bite-size lumps, and coated in kinako (toasted soybean flour) to make a jellied confection.
Kirkley first tried mixing up the starch in the traditional way. "It's an extremely unique texture. It's snotty. It's really, really creepy," he said. "The Japanese and their textures—they like the weird textures."
He ended up adding gelatin to the mix, which turned it into "a gummy-bear kind of texture—so it still has the stretch you get from the starch, but it's got a little bit more appealing mouth feel."
Warabi starch doesn't really have any taste, Kirkley said, which meant that he didn't have to think about what flavors would go with it. He decided to make a mussel-clementine gummy. "When I'm dealing with modern starches, I try to have something that people can connect to," he said. "Orange and mussel I consider to be pretty classical."
The clementine liquid was simply clementine juice that Kirkley filtered using agar-agar; he also reserved the liquid from cooking mussels and simmered it with more mussels to intensify the flavor, then clarified it with egg whites. After combining the clementine and mussel liquids, he heated them with the warabi starch and gelatin until the mixture thickened, cooking it until all the starch was activated and then piping it into hemispheric molds to cool.
Kirkley discovered that the gel was so sticky the only way he could get it out of the molds was to put it in a blast freezer for a few minutes. Usually freezing gelatin breaks its structure, he said, but in this case the starch helped to hold everything in place. Once he had the pieces out of the molds, all he had to do was put them together; their own stickiness was enough to bind the halves into a sphere.
The final step was rolling the spheres in orange-mussel powder. Kirkley dehydrated mussels in the microwave until they hardened, then threw them in a blender; the orange powder came from orange peel blanched first in water (to get the bitterness out), then in simple syrup, before being dehydrated and blended. He topped each mussel-clementine sphere with a dot of gel made from the clementine liquid and a tiny piece of candied orange zest.
While Kirkley liked the texture of the final product, he thought the mussel flavor was a little too strong. If he were planning to put the dish on the menu, he'd do some refining of the recipe—but that's probably not going to happen. "This will probably be my last time using warabi starch," he said.
Still, he added, "It's good to know it's out there. If I was ever coming up with a dish where I was like, boy, I really need this to be weird and runny, I know where to get it now."
Ryan LaRoche of NoMi Kitchen, working with celery. "It's been getting crazy with these ingredients I've seen, and I thought it would be nice to just return to forced creativity with something as mundane as celery," Kirkley said. "I think it's harder, actually. Roasting a chicken is more noble than any wacky sous vide thing."