The chufa plant is a type of sedge that produces small tubers known as chufas, chufa nuts, or tiger nuts. They're used in Spain to make the groundnut drink horchata (Mexican horchata, on the other hand, is usually made from rice). Aside from that, chufas don't show up in many other culinary applications—though a lot of animals, particularly turkeys and carp, love them.
B.K. Park, who'd never worked with chufas, couldn't find them locally, so he ordered them from Spain; they arrived at his Ukrainian Village restaurant looking a little like small, withered almonds. Park originally wanted to grind them into a powder, but that didn't work. So he decided to stick with what he knows best: "I'm going to make sushi with it," he said. Park boiled and soaked the chufas with a little butter, then ground them up and used the mixture in place of rice in four types of sushi.
"It's kind of like a nut, but it's a different texture, different flavor," Park observed. "I've never seen it before, actually. It's a very strange texture, but the flavor is good."
To keep the mixture from getting too gummy, Park opted for a medium as opposed to fine grind. As with sushi rice, he wanted the chufa mixture to have some texture. "Pasta, if you cook it all the way done, is too soft. Sushi rice is the same. It's not cooked all the way, so it's got nice texture to it. We have to be really careful about controlling the water amount and the timing and everything."
Using the chufa mixture in sushi was difficult, Park said. It was too dry at first, so he added some water, soy sauce, vinegar, and sugar to make it sticky enough—and to complement chufa's inherent nuttiness with sweet and sour flavors. And while he usually uses raw fish for his sushi, Park cooked most of the fish for this application because he thought it would better suit the chufa.
Pulling apart king crab for his first roll, Park noted, "I never use a knife because it kills the texture. I always use fingers." He sauteed the crab in butter and topped it with a bit of fresh wasabi. He left the sweet shrimp in another roll raw, but topped them with spicy mayonnaise and torched them to make them a little firmer and add a slightly grilled flavor. He finished the roll by topping it with a fresh salsa of tomato, onion, sea salt, and olive oil.
The third roll was the most complicated, with thinly sliced salmon wrapped around chufa and a baked mixture of scallops, spicy mayo, smelt roe, and scallions. He also used steamed eel in the roll, with a bit of Asian pear soaked in yuzu juice. "This is the last course, because it's a little sweet, a nice clean finish," Park said. "Like dessert sushi."
Park was pleased with the results of his experimentation. He noted that chufa has a lot more texture than rice, which "makes you chew." The more you chew, the more flavor comes out—not only from the chufa, but from the other parts of the roll.
He's considering doing a chufa special sometime soon. "I have a lot left over."
Shin Thompson of Logan Square's Bonsoiree, working with burdock root, also known as gobo. Park isn't the biggest fan of the ingredient, which is why he challenged Thompson to work with it: "It's a very strong and very powerful flavor. I think he can make a better flavor [with it]."