The Hibiscus Cake
If you have never tasted iced hibiscus tea, or agua de Jamaica, as it is called throughout Mexico, you are in for a treat. I discovered it for myself at a tiny taco stand in San Diego. Immediately enchanted with its rich ruby color and invigorating tartness, I couldn’t wait to make it for myself at home. The tea is made from dark red dried hibiscus blossoms, also known as flor de Jamaica, and it’s no more difficult to make than a cup of Earl Grey.
Steep dried blossoms in hot water with fresh ginger, add lime juice, and then sweeten with a little sugar. For a fun hybrid between a Latin American tres leches cake and a kitschy American Jell-O poke cake, I simmer the sweet hibiscus tea until it’s syrupy, and then set it with gelatin before pouring it over delicate layers of lime chiffon cake. It’s cool, tart, and refreshing, with a subtle, gingery bite.
LIME CHIFFON CAKE
2 cups [200 g] sifted cake flour
13/4 cups [350 g] sugar
2 tsp baking powder
1/2 tsp fine sea salt
6 eggs, at room temperature
1/2 cup [120 ml] vegetable oil
1/2 cup [120 ml] water
1/4 cup [60 ml] freshly squeezed lime juice
1 tsp grated lime zest
1 tsp vanilla extract
1/2 tsp cream of tartar
11/2 cups [360 ml] water
1 cup [60 g] dried hibiscus flowers
One 2-in [5-cm] chunk fresh ginger, peeled and coarsely chopped
5 tsp unflavored granulated gelatin
1 cup [200 g] sugar
1/2 cup [120 ml] freshly squeezed lime juice
11/2 cups [360 ml] chilled heavy cream
1/2 cup [120 g] chilled crème fraîche
1/4 cup [50 g] sugar, plus more if needed
2 Tbsp freshly squeezed lime juice
1/4 cup [35 g] finely minced candied ginger
Thin lime slices for decorating.
Position a rack in the center of the oven. Preheat the oven to 325°F [165°C]. Lightly grease the bottoms of two 9-in [23-cm] round cake pans and line the bottoms with parchment paper. Do not grease the sides of the pan.
To make the cake:
Sift together the flour, 11/4 cups [250 g] of the sugar, the baking powder, and the salt into a large bowl. Set aside.
Separate 5 of the eggs. Put the 5 egg whites in the bowl of a stand mixer and set aside.
Place the 5 egg yolks in a medium bowl. Using a large balloon whisk, beat the egg yolks together by hand with the remaining whole egg, the oil, water, lime juice and zest, and vanilla until thick and smooth, about 1 minute. Make a well in the center of the dry ingredients and scrape the wet ingredients into the well. Beat together with a hand mixer set at medium speed until thick and smooth, 1 to 2 minutes.
In a stand mixer fitted with the whisk attachment, beat the egg whites and cream of tartar on low until soft peaks form. With the mixer still running, add the remaining 1/2 cup [100 g] sugar to the egg whites, 1 tablespoon at a time, until they are fluffy and light and hold firm peaks when the beaters are lifted from the bowl.
Using a rubber or silicone spatula, gently fold one-third of the egg whites into the cake batter to lighten it. Fold in the remaining whites just until blended, taking care not to deflate them or to overmix the batter.
Divide the batter between the prepared pans and smooth the tops with a spatula. Bake for 20 to 25 minutes, until the cake springs back when lightly touched with a finger and a wooden skewer inserted into the center of each cake comes out clean. Invert the pans onto a wire rack, allowing the cake layers to cool completely while they are upside down (do not remove the pans). When the layers are cool, run a thin, offset spatula around the edges of each cake to loosen from the pan. Carefully remove the cake layers from the pan and peel off the parchment paper.
To make the syrup:
In a 2-qt [2-L] saucepan, combine the water, hibiscus flowers, and ginger and bring to a boil over medium-high heat. Decrease the heat to low and simmer until the water is a deep red, about 10 minutes. Remove from the heat and cover. Let cool completely. Strain through a fine-mesh sieve into a small bowl, pressing the hibiscus flowers to extract all the liquid. Discard the flow – ers and ginger. Transfer 1/3 cup [80 ml] of the cooled hibiscus tea to another small bowl and sprinkle it with the gelatin. Let it stand for a few minutes to soften.
Combine the remaining hibiscus tea and the sugar in a 2-qt [2-L] saucepan over medium heat, bring to a boil, and stir until the sugar is dissolved. Decrement the heat to medium-low and simmer until lightly syrupy, 3 to 5 minutes. Add the lime juice and gelatin mixture, stirring just until the gelatin is dissolved. Pour the mixture into a measuring cup with a spout and let cool to room temperature.
Line two clean 9-in [23-cm] round cake pans with plastic wrap. Place the cake layers back in the cake pans, top-side up. With the fat end of a chopstick, pierce both layers all over the top, halfway through the cake. Pour half of the hibiscus syrup over each layer. Refrigerate for at least 3 to 4 hours and preferably overnight, until the cakes are very cold and the gelatin is firm.
To make the topping:
An hour or two before serving, chill the bowl and whisk attachment from a stand mixer for 15 minutes. Beat together the heavy cream, crème fraîche, and sugar on medium speed until soft, mounding peaks form. With the mixer running, beat in the lime juice. Taste for sweetness, adding more sugar if needed, 1 tablespoon at a time, until the topping has the sweetness you like.
Grasping the plastic wrap, pull each cake layer from their pans. Carefully ease the first layer onto a cake stand or cake plate, discarding the plastic wrap. Spread with about one-third of the whipped-cream topping. Top with the second layer of cake and frost the tops and sides of the cake with the remaining topping. Sprinkle the top of the cake with the minced candied ginger and lime slices. Cover lightly with plastic wrap and refrigerate until ready to serve. The cake is best served within 2 hours of being frosted, but will keep, covered and refrigerated, for up to 2 days.