In a food processor combine the flour and salt. Pulse 5 times
Add the cubed COLD butter then pulse until you get a coarse meal texture. About 5-7 1 second pulses
Add the butter and flour mixture to a bowl then add the cider vinegar and ¼ cup of ice water. Mix well with a fork
Continue adding ice water 1 tablespoon at a time mixing well in between each addition just until the dough starts to come together. It will look a bit shaggy, you don't want it too wet
Form the dough into a ball and refrigerate for at least 1 hour or up to 3 days
Making the Sweet Potato Filling
Preheat the oven to 400°F and line a baking sheet with aluminum foil or parchment paper
Roast the sweet potatoes for 1 - 1.25 hours or until a brown thick liquid starts to ooze out of the sides and the potatoes feel soft. Set them aside to cool
While the potatoes are roasting make the brown butter
Melt the butter in a sauce pan over low - medium heat. The butter will start spattering. Give it a couple stirs. Once the butter becomes quiet it's ready to remove from the heat
Once the potatoes have cooled enough to handle scoop the inside out into a food processor. Blend on low until smooth
Add the sweet potato mix to a bowl. Mix in the remaining filling ingredients and whisk together until combined
Blind Baking the Crust
Preheat the oven to 350°F
While the sweet potatoes are cooling you can roll out the crust, fit it to the pan and crimp the edges with your fingers or a fork
Place a sheet of parchment paper across the bottom of the dough then add pie weights and bake for 25 minutes. Remove and set aside
Filling and Baking the Pie
Pour the sweet potato filling into the blind baked pie crust then bake 1 hour
The pie is ready when the center is just slightly wobbly. Let pie cool before adding meringue and serving
Making the Meringue
In the bowl of a stand mixer fitted with the whisk attachment add the egg whites, cream of tartar, vanilla extract and salt. Beat on medium speed until it forms soft peaks
While the egg whites are beating pour the sugar and water into a small sauce pan and bring to a boil without stirring. Once the mixture reaches 250°F (about 5 minutes) remove it from the heat
With the mixer on low speed slowly pour the sugar mixture down the side of the bowl until fully combined
Turn the mixer up to medium and beat until stiff peaks form
Spoon the meringue over the top of the pie in whatever kind of design you'd like then toast the meringue using a kitchen torch
Notes
Use homemade or store bought pie crust.Using a food processor is important for texture in this sweet potato pie. This pie is great with or without meringue.