: In a medium-sized bowl, whisk together the flour, sugar, lemon zest or oil, and salt. Using a pastry fork or pastry blender, your fingers, or an electric mixer, cut in the cold butter, working the mixture till it's crumbly; a few larger chunks of butter
In a small cup or bowl, whisk together the egg yolk and the vanilla extract. Stir this mixture into the pastry dough. Roll or press the dough onto the bottom and at least 1 inch up the sides of a 9- to 10-inch springform pan, or 9-inch round cake pan. Use
Bake the chilled crust for 16 to 18 minutes in a preheated 375°F oven, until it's golden brown. Check it midway through the baking time; if it's developed any big bubbles, puncture them. Remove the crust from the oven (leave the oven on), and cool it on a
: In a medium-sized bowl, or the bowl of an electric mixer, whisk together the lemon juice, lemon zest or oil, and the sugar. Whisk in the eggs, then the sour cream. Pour the filling into the cooled tart shell. Don't overfill the shell; if any filling see
Return the tart to the 375°F oven, and bake it for 18 to 20 minutes. The filling should look "set," but still wobble slightly in the middle. Remove the tart from the oven, and set it on a rack to cool for 1 hour. Refrigerate it; top the tart with strawber
: In a saucepan or microwave-safe bowl, combine the brown sugar and juice. Sprinkle the gelatin over the juice, and let it swell and soften for 5 minutes or so. Heat the mixture over low heat or in the microwave until the gelatin dissolves, then remove it
: If you're using strawberries, wash, hull, and slice them; you can leave them whole if they're small. Brush a thin layer of glaze (about 2 tablespoons) over the tart. Mix the berries with the remaining glaze, then arrange them, one by one, atop the tart.
After about 30 minutes of chilling, remove the tart from the fridge, and brush the berries with the reserved glaze. This will keep them fresh and glistening for 12 hours.