Preheat the oven to 350°F., then bake the pie shell for 15 minutes. Set aside to cool.

Add 1 tablespoon white vinegar to a clean rag and thoroughly wipe the beaters and inside of a stainless or glass mixing bowl. This will remove any fat, eliminating problems when you whip the egg whites. Set aside.

Place a 3 or 4-quart saucepan on the stovetop, over medium-low heat. Add the sour cream, sugar, flour, and egg yolks. Using a heat-resistant rubber spatula, stir contents to combine.

Add the raisins to the pot and continue cooking, stirring occasionally, until thick, about 10 minutes.

Meanwhile, add the egg whites to the clean mixing bowl. Using a stand mixer or electric hand mixer fitted with a whisk attachment, beat on high speed until whites are frothy.

Add the cream of tartar and continue beating on high speed until soft peaks form. With the mixer running, slowly add the sugar. Continue beating until stiff peaks form, about 2-3 minutes.

Pour the custard into the pre-baked pie shell and spoon the meringue in a dome shape over the filling.

Bake in the preheated oven for 15 minutes. Remove pie from the oven and transfer to a wire rack to cool for at least 1 hour. Refrigerate for 1-2 hours after that.