- 1-1/4 Cup All-Purpose Flour
- 3 Tbsp Sugar
- 1/4 Tsp Salt
- 1/2 Cup Unslated Butter, Chilled, Cut into 1/2" Cubes
- 1 Large Egg Yoolk
- 1 Tblsp Whipping Cream
- 1/2 Cup Whipping Cream
- 2 Tbsp Cornstarch
- 2 Large Eggs
- 4 Large Egg Yolks
- 1 Tsp Vanilla Extract
- 1/2 Cup White Balsamic Vinegar
- 3/4 Cup Water
- 3/4 Cup Sugar
- 1/4 Cup Unsalted Butter
- 2 Large Strawberries, hulled and sliced
- 2 1/2 Pint containers Blueberries
- 1 1/2 pint container Raspberries
Combine flour, sugar, and salt in processor; blend 5 seconds. Add butter and blend, using on/off turns, until coarse meal forms. Add egg yolk and cream. Using on/off turns, blend until moist clumps form. Gather dough into ball. Press dough evenly into 9-inch-diameter tart pan with removable bottom. Pierce dough all over with fork. Chill 1 hour.
Preheat oven to 375°F. Bake crust until golden, pressing with back of fork if crust bubbles, about 22 minutes. Cool.
Stir cream and cornstarch in medium bowl until cornstarch dissolves. Add eggs, egg yolks, and vanilla; whisk to blend.
Boil vinegar in heavy medium saucepan until reduced to 1/4 cup, about 3 minutes. Add 3/4 cup water, sugar, and butter. Stir until butter melts; return to boil. Gradually whisk vinegar mixture into egg mixture; return to pan. Whisk until custard thickens and boils, about 1 minute. Strain into bowl; cool. Spread custard in prepared crust. Cover and chill tart at least 3 hours and up to 1 day.
Arrange strawberry slices in star pattern in center of tart. Arrange raspberries in star pattern. Surround with blueberries. Cover loosely and chill until ready to serve. (Can be made up to 6 hours ahead.)