Sous Vide Lemon Buttermilk Saffron Tart
Cooking time: 1 hour, chilling time 4 hours.
Buttermilk pie tart:
- 1 1/4 cups all-purpose flour
- 1 tablespoon sugar
- 1/2 teaspoon kosher salt
- 1/2 cup (1 stick) chilled unsalted butter, cut into pieces
- 1/4 cup buttermilk
Filling and assembly:
- 2 tablespoons all-purpose flour, plus more
- 6 large egg yolks
- 3 large eggs
- 1 1/4 cups buttermilk
- 1 1/4 cups sugar
- 1 tablespoon finely grated lemon zest (we used meyer lemons)
- 1/3 cup fresh lemon juice
- 1/4 teaspoons kosher salt
- Pinch of saffron threads
- 2 tablespoons unsalted butter, melted, cooled slightly
- Whipped cream (for serving)
For buttermilk pie dough:
1. Pulse flour, sugar, and salt in a food processor to combine. Add butter and pulse until mixture resembles coarse meal with a few pea-size pieces of butter remaining.
2. Transfer to a large bowl and add buttermilk. Mix with a fork, adding more buttermilk by the tablespoon if needed, just until a ragged dough comes together; knead very lightly until no dry spots remain. This can be made 2 days in advance if put in the refrigerator or kept for up to a month in the freezer.
For filling and assembly:
1. Preheat oven to 325°F. Roll out pie dough on a lightly floured surface to a 14” round. Transfer to a 9” pie dish, allowing dough to slump down into dish. Trim dough, leaving about 1” overhang. Fold overhang under and crimp edge. Perforate bottom all over with a fork.
2. Set Nomiku up and turn temp to 82°C (179°F).
3. Line crust with parchment paper or foil, leaving an overhang, and fill with pie weights or dried beans. Place pie dish on a rimmed baking sheet and bake until crust is dry around the edge, 20–25 minutes. Remove parchment and weights; bake until surface looks dry, 10–12 minutes longer.
4. Meanwhile, blend egg yolks, eggs, buttermilk, sugar, lemon zest, lemon juice, salt, and saffron in a blender until smooth. With motor running, add 2 tablespoons flour, then butter. Tap blender jar against countertop to burst any air bubbles in filling and pour into a bag to vacuum seal. We like to use a freezer zip bag and use the water displacement method to get the air out. Simply dip the bag in water up to the seal and the barometric pressure of the water will push all of the air out. Run fingers over the seal twice to ensure a tight seal.
5. Once Nomiku comes to temperature, drop ingredients in water bath for 30 minutes. Take the bag out at the 15 minute mark and squeeze the bag with a heat-safe glove on or with tongs to mix the ingredients around.
6. Pour custard into pie crust and refrigerate for 4 hours.
7. Whip 1 ½ cups of whipping cream with desired amount of powdered sugar, decorate with mint leaf and lemon zest if desired, top pie and enjoy!