Preheat oven to 325 degrees F.
In a small saucepan, bring the water and salt to a boil. Add the grits and cook for 4 minutes, stirring constantly. Add the butter and cook for 1 additional minute. Set aside and cool slightly.
In a small bowl, stir together the sugar, flour, eggs, buttermilk, and vanilla. Slowly stir into the cooled grits. Pour into the pie shell and bake for 35 to 40 minutes, or until set. Serve warm or cold with whipped cream and strawberries as a garnish, if desired.