Frozen Lemon Parfait with Vanilla Pearl Tapioca

To prepare the parfaits: Put the lemon zest and sugar into a stainless steel pan and rub together with your hands to allow the lemon oil to scent the sugar. Put the gelatin in 1/8 cup of ice water to soften. Put the sugar mixture, eggs, and lemon juice a medium saucepan and whisk until combined. Place over medium heat and continue whisking until the mixture reaches 180 F. Take off the heat and stir in the gelatin. Stir gently to dissolve the gelatin completely, then let the mixture cool to 140 F. It will thicken as it cools. Using an immersion blender, blend in the butter, a little at a time, to create an emulsion. The mixture will change consistency, becoming smoother, and lighten in color. Spoon into a flexipan mold with fifteen 3-inch round cups. Smooth the tops, and freeze 4 hours, or overnight.

To prepare the tapioca: Place the tapioca pearls in a large pan and cover with 2 inches of cold water. Let stand overnight in the refrigerator to rehydrate the tapioca. Drain the water and place in a large saucepan with the milk. Scrape the seeds from the vanilla beans into the pot, then drop in the bean pods. Bring to a simmer, then turn off the heat. Allow to sit for 30 minutes, stirring periodically with a slotted spoon so that a skin does not form. Slowly reheat and bring almost to a boil, stirring constantly. Turn off the heat once again and let cool. Repeat the heat-cool cycle a third time.

In a bowl, whisk together the sugar, egg yolks, and cornstarch. Whisk in a large spoonful of the hot tapioca milk, then slowly add the egg mixture to the tapioca, stirring constantly to blend. Place over medium heat and stir constantly as the mixture heats just until it begins to boil. Add the salt and vanilla. Pour into a warmed baking dish and place in a larger dish of very warm water. Cover with plastic wrap and punch a few holes in the wrap to allow the heat to escape. Allow to cool. Pick out the vanilla bean pods. If the tapioca is too thick once it is cooled, thin with a little milk to desired consistency.

To prepare the sauce: Place the corn syrup in a heavy saucepan and add the sugar. Scrape the seeds from the vanilla bean into the mixture. Heat over medium-high heat until the sugar melts and turns a warm caramel color. Whisk in the butter and whipped cream. Put in a squeeze bottle and set aside; keep warm.

To serve: Cover a work surface with parchment or waxed paper and put the cake crumbs on the paper. Unmold the frozen lemon parfaits and roll the rims in the crumbs to cover. Place a parfait to one side on each chilled serving dish. Hollow out the centers of the parfaits and mound tapioca into the centers. Drizzle the plates with caramel sauce, starting over the tapioca and drawing out into a large spiral on the dish. Garnish with lemon zest strips and small flowers or mint leaves.