Soothing chamomile and cloudlike meringue lend delicacy to this tart lemon classic. A rustic cornmeal crust grounds the dessert.
On a lightly floured work surface, roll cornmeal dough to 1/8-inch thickness. Fit into a 9-inch pie dish. Trim edges, leaving a 1-inch overhang. Tuck overhang under dough so edges are flush with rim, and crimp edges. Lightly prick bottom of dough with a fork. Refrigerate for 30 minutes.
Preheat oven to 375 degrees. Line dough with parchment, and fill with pie weights or dried beans. Bake until edges begin to turn gold, 15 to 18 minutes. Carefully remove weights and parchment. Bake until crust is golden brown, 12 to 15 minutes. Let cool completely on a wire rack. (Cornmeal crust can be stored overnight.)
Bring milk to a boil in a medium saucepan, and remove from heat. Add tea bags, cover, and steep for 5 minutes. Strain through a fine sieve, pressing on tea bags to extract liquid. Discard tea bags.
Combine cornstarch, 1 cup sugar, and 1/4 teaspoon salt in a medium saucepan. Whisk in milk mixture. Set over medium-high heat, and cook, stirring constantly, until bubbling and thick, about 7 minutes total (about 2 minutes after it comes to a boil).
Whisk yolks in a medium bowl until combined. Pour in milk mixture in a slow, steady stream, whisking until completely incorporated. Return mixture to the saucepan. Cook over medium heat, stirring constantly, until it returns to a boil, 1 to 2 minutes.
Remove from heat, and stir in lemon zest and juice. Add butter, 1 tablespoon at a time, whisking until butter melts before adding next piece. Let custard cool in saucepan on a wire rack, whisking occasionally, for about 10 minutes.
Pour custard into cornmeal crust. Press plastic wrap directly on surface of custard. Refrigerate until custard filling is chilled and firm, at least 4 hours (or overnight).
Just before serving, combine whites and remaining cup plus 2 tablespoons sugar in a mixer bowl. Set over a saucepan of simmering water. Whisk until sugar dissolves and mixture is warm, about 3 minutes. Transfer bowl to a mixer, and add vanilla, cream of tartar, and a pinch of salt. Whisk on medium-high speed until shiny, stiff peaks form, about 7 minutes.
Spread meringue over pie. Crush dried chamomile flowers until powdered, and sprinkle over meringue. Garnish with fresh chamomile flowers if desired. Serve immediately.
The egg whites in this recipe are not cooked. This dish should not be prepared for pregnant women, babies and other young children, the elderly, or anyone whose health is compromised.