Beat together sour cream, 3/4 cup sugar, egg, 2 tablespoons flour, vanilla extract and salt in a mixing bowl until smooth. Gently fold the blueberries into the sour cream mixture. Spoon the filling into the unbaked pie crust.
Bake in the preheated oven for 25 minutes.
While the filling is baking, prepare the streusel crunch topping: In a medium bowl combine 3 tablespoons flour and 2 tablespoons sugar. Cut the cold butter into the flour mixture until crumbly. Fold in the chopped pecans. After the filling has baked 25 minutes, sprinkle the streusel crunch topping over the top of the pie.
Bake until the topping is golden brown, about 15 additional minutes.