This is a very different type of crumble from the one your grandmother might have made—the rhubarb is gently poached in a lemongrassinfused syrup and then elegantly layered in a glass with a lemon- and lime-flavored cream and topped with a crisp pistachio crumble. It makes a deliciously elegant and modern twist on an old favorite.
– PREPARATION TIME 20 minutes, plus at least 3 hours chilling.
– COOKING TIME 50 minutes.
– 3½ cups peeled rhubarb cut into 1-inch-long pieces, with the trimmings reserved.
– ½ cup sugar.
– 1 lemongrass stalk, split and bruised.
– FOR THE LEMON AND LIME CREAM.
– ¾ cup heavy cream.
– 2 tablespoons sugar.
– 2 tablespoons lemon juice.
– finely grated zest of ½ lemon.
– finely grated zest of ½ lime.
– FOR THE PISTACHIO CRUMBLE.
– ¾ cup plus 1 tablespoon confectioner’s sugar.
– ¾ cup plus 1 tablespoon all-purpose flour.
– a pinch salt.
– ¾ cup very finely ground blanched almonds.
– ⅓ cup shelled pistachios, roughly chopped.
– 7 tablespoons unsalted butter, soft.
Step 2: Put the rhubarb, rhubarb peelings, sugar and lemongrass in a sauté pan and just cover with water. Heat over low heat until simmering, then simmer 15 to 20 minutes until the rhubarb is just tender but keeps its shape. Strain the rhubarb through a fine strainer into the cleaned pan, then return the syrup to the heat and cook until it reduces by half and is thick and syrupy. Meanwhile, discard the rhubarb peelings and the lemongrass and put the rhubarb in a shallow nonmetallic dish. Pour the reduced syrup over the top of the rhubarb and leave to cool while you make the crumble.
Step 3: Heat the oven to 315°F. Put all the crumble ingredients in a large mixing bowl and rub gently with your fingertips to make a coarse crumb mixture. Tip the crumb mixture into a baking sheet in an even layer and bake 20 to 25 minutes until it is golden brown. Turn the crumble mixture, bringing the edges into the middle and then spreading it out into an even layer again, every 6 to 8 minutes to make sure it bakes evenly. Remove the baking sheet from the oven and leave the crumble to cool completely until it is crunchy.
Step 4: Take the cream-filled glasses out of the refrigerator and top with the rhubarb. Drizzle with the syrup and finish with the crumble, gently sprinkling it over the top. Serve immediately while the crumble topping is still crunchy.