The cupuacu tree is in the same family as the cacao tree, but though the fruits are similar looking, cupuacu—unlike cacao—is usually harvested for its pulp rather than its seeds. Those can be processed to make a chocolatelike substance called "cupulate," but it's not widely available. Neither, for that matter, is the cupuacu fruit. While it's become more popular in the last several years for its nutrient value—it's high in antioxidants, essential fatty acids, and several vitamins and minerals—the fresh fruit isn't imported to the U.S., and it's easiest to find as a powder.
Bobby Schaffer, pastry chef at Grace, challenged with cupuacu by Patrick Fahy (pastry chef at Sixteen), tracked down a frozen puree sold by Amafruits, a specialty importer based in Orland Park. "It's actually really acidic, so it kind of makes you pucker immediately," Schaffer said. "It's not the nicest thing; it needs some sugar to balance it out." The flavor, he said, was reminiscent of pear and quince, but the acidity reminded him of a lemon. On top of all that, it smelled like rum.
Schaffer tried making a curd with the cupuacu, but found the sour fruit to be surprisingly buttery tasting. "It was interesting because I caramelized some sugar and added that, and it took on a buttery, rich flavor, and once I added the butter to it, it was too rich. The flavor of the cupuacu didn't really come through as much as I would have liked it to."
Instead, Schaffer settled on a semifreddo, using the dessert's fat and sugar to balance out the acidity of the cupuacu. He juiced the fruit and combined it with whipped egg yolks and sugar syrup, then folded in whipped cream and froze the mixture, cutting out disks of semifreddo once it was frozen. (Schaffer also experimented with filling the semifreddo with chocolate, but decided against it in the end.) "I paired it with flavors that were complementary to that tropical rum note," he said. That meant wild huckleberries, sorrel sorbet, elderflower syrup, Asian pear, and fresh sorrel. Schaffer also dehydrated some of the semifreddo and sprinkled it with crushed black lime to introduce a crunchy element to the dish.
"They're all strong flavors in their own regard, and you get each flavor, but they also complement each other," Schaffer said after he tasted the dish. "The acidity of the sorrel cuts through that semifreddo. The cupuacu is such a strong flavor that it can tend to linger in your mouth, so you get the flavor without a lingering aroma of the cupuacu. The pear's nice. It's a subtle undertone; it also adds a lot of texture with its crunch. It complements that pear note that you get in the cupuacu."
Schaffer liked cupuacu enough that he wants to experiment with it more, especially in combination with chocolate. Besides, he said, "I've got to come up with something . . . we've got like ten pounds of cupuacu hanging out."
Thomas Raquel, pastry chef at Acadia, working with horned melon. It's been used at Grace in savory applications, like a horned-melon snow paired with king crab—but Schaffer said that while he's tasted it, he's never worked with it. "It's got a strange appearance, but the flavor is reminiscent of cucumber."
85 g egg yolks
85 g sugar
15 g water
Cook sugar and water to 120 C. Begin whipping yolks in a mixer and slowly stream in sugar syrup. Allow to whip until cool.
75 g cupuacu juice
120 g sugar
600 g heavy cream
2 g salt
Whip heavy cream to soft medium peaks and set aside.
Add cupuacu juice to the whipped egg yolks along with the sugar and salt. Once combined add a small amount of the whipped cream and fold in. Finish with the remainder of the whipped cream. Pour into small pan and allow to freeze. Once frozen, use a ring to cut out disks of semifreddo.