Rhubarb au Gratin with Lemon Balm-Elderblossom Ice Cream

To make the ice cream: Pull the leaves from the lemon balm. Bring a large pot of salted water to a boil and add the lemon balm leaves; boil 2 minutes, remove, and plunge the leaves into ice water. Strain, then spread the leaves on paper towels and pat completely dry.

Whisk the egg yolks and sugar together until the sugar has melted. Heat the milk and cream together in a saucepan over medium-high heat. When the milk and cream mixture just reaches a boil, remove from heat. Whisk a large spoonful of the hot mixture into the egg yolks and sugar to temper them, then slowly add the yolks and sugar to the hot milk and cream, whisking constantly to blend in the eggs without heating them so suddenly they scramble. Add the elderberry blossoms and cook over medium-low heat for 10 minutes to infuse the flavor, stirring occasionally. Strain the mixture through a fine-meshed sieve into the bowl of a food processor or blender and add the blanched lemon balm leaves. Puree. The mixture will be pale green. Strain again and freeze in an ice cream machine according to manufacturer’s directions.

To make the tuile cups: Preheat the oven to 350 F. Invert a large baking sheet and spray the back very lightly with vegetable oil spray; wipe once to remove any excess. In a medium saucepan or skillet, melt the butter and sugar over low heat. Transfer the mixture to a medium bowl, stir in the flour, and add the egg whites. Whisk until the batter is smooth.

Using a large serving spoon, drop circles of batter on the prepared sheet. With a spatula or the back of the spoon, spread the batter into thin circles. Bake until golden brown, about 12 minutes. Quickly remove the cookies from the pan and, while they are still hot, place them over an inverted glass or cup and press them into a cup shape. Let them cool in this position. If they become too stiff to bend before you are finished, return them momentarily to the oven to warm. When the cookies are set, remove them and let cool completely. Store sealed in a plastic bag in a cool place until ready to use.

To prepare the rhubarb compote: Chop the rhubarb stems into 1-inch pieces (do not use any other part of the plant). Place in a saucepan over medium-low heat with the sugar and water and cook 5 minutes. Add the orange juice and the squeezed orange sections. Continue cooking until the liquid has nearly evaporated and become syrupy. Remove and set aside; take out the orange sections.

To prepare the sabayon: In the top of a double boiler over barely simmering water, whisk the egg yolks and sugar until the sugar has dissolved and the mixture is smooth. Add the wine and cook, whisking constantly, until the mixture thickens and coats the back of a spoon. Remove from heat and whisk for another minute or two until the mixture has cooled slightly.

To serve: Heat the broiler to high. Place a bed of rhubarb on each of 8 serving plates set on a baking sheet. Spoon sabayon over the rhubarb and place under the broiler just long enough to brown tops slightly. (Alternatively, use a small kitchen torch to brown the tops.) Put a tuile cup on each caramelized bed of rhubarb and fill with a scoop of ice cream. Dust a candied orange slice with confectioner’s sugar and stand the slice edgewise in the ice cream.

Candied Orange Slices

To make the candied orange slices: Cut the oranges into very thin slices crosswise and pick out any seeds. Place the oranges in a saucepan and cover with cold water; bring to a boil and cook 5 minutes. Drain, rinse with cold water, cover with cold water, and again bring to a boil and cook 5 minutes. Drain well and set aside to cool.

In a medium, heavy saucepan, combine the sugar, water, and corn syrup. Stir over low heat until the sugar is dissolved. Bring to a boil and cook 2 minutes. Pour the sugar syrup over the orange slices and put over low heat. Cook 1 hour. Remove, cool, cover, and let stand overnight at room temperature.

The next day, preheat the oven to very low. Bring the oranges and syrup back to a boil, reduce heat to low, and cook 1 hour. Spread the orange slices on a wire rack over parchment paper or foil in a baking pan. Turn off the oven and place the pan in the oven to dry the slices. When dry, roll in sugar. Store in a sealed container between layers of parchment; the slices will keep up to a month. This same process may also be used with other citrus fruit.