2teaspoonsfinely grated fresh lemon zestsave juice
Filling
3tablespoonsunsalted butter, cut into small chunks(42 grams)
5 ¼cupscherries, fresh or frozen, 28 oz
¾cupplus 1 tablespoon sugar(160 grams)
1tablespoonlemon juice (omit if using sour cherries)
2tablespoonscold water
3tablespoonscornstarch
Instructions
Beat together butter and ⅓ cup sugar with an electric mixer at medium speed until pale and creamy. Reserve 1 tablespoon beaten egg for egg wash and beat remaining egg into butter mixture. Add vanilla, salt and lemon zest.
Add flour and mix on low to form a dough. At this point, the dough should be quite thick. It gets a little more delicate when you start working with it, so do keep it cold.
Take out ⅓ of the dough so that you have 1 part and 2 parts. Form dough sections into a 5- to 6-inch disk. Wrap disks in plastic wrap and chill until firm, at least 30 minutes.
Heat butter in a 12-inch nonstick skillet over moderate heat until foam subsides, then add cherries and sugar. Simmer, stirring, until sugar dissolves. If you are using the lemon juice, add the lemon juice. Continue to simmer until cherries are tender but not falling apart, about 8 minutes.
Stir together water and cornstarch to form a thick paste, then stir the paste into hot cherries, stirring frequently, 2 minutes. Cool filling quickly by spreading it in a shallow baking pan and chilling until lukewarm, about 15 minutes.
Roll out 1 piece of dough (keep remaining piece chilled) between 2 sheets of wax paper or parchment into a 12-inch round. Remove top sheet of paper and invert dough into a greased 9 inch tart pan. Trim overhang to ½ inch and fold inward, then press against side of pan to reinforce edge. Chill tart shell. Roll out remaining dough in same manner and remove top sheet of paper, then cut dough into 10 (1-inch-wide) strips and slide dough, still on wax paper, onto a baking sheet. Chill strips until firm, about 5 minutes.
Put a foil-lined large baking sheet in middle of oven and preheat oven to 375°F (don't skip the foil lined pan as the crostata will boil over a bit).
Spread filling in chilled tart shell and arrange 5 strips 1 inch apart across filling, pressing ends onto edge of tart shell. Arrange remaining 5 strips 1 inch apart diagonally across first strips to form a lattice with diamond-shaped spaces. Trim edges of all strips flush with edge of pan. Brush lattice top with reserved beaten egg and sprinkle crostata with remaining tablespoon sugar.
Bake crostata in pan on baking sheet in oven until pastry is golden and filling is bubbling, about 1 hour. (If lattice and edges look too brown after 30 minutes, loosely cover with foil.) Cool crostata completely in pan on a rack, 1 ½ to 2 hours, to allow juices to thicken.