cider vinegar, vanilla and bourbon (if using). pour into a bowl (so that it cools faster) and set the mixture aside to cool a little, about 5 to 10 minutes. then, whisk in one egg at a time until combined. pour mixture into prepared pie shell.
bake: for 40 to 45 minutes. the pie is done with the edges are set and puffed slightly and the center is slightly firm to the touch but still has some jiggle to it. cool on a rack. serve slightly warm or room temperature. 