Wash potatoes well and cut them into bite-sized pieces.
Boil the potatoes in salted water for approximately 10 minutes, or until tender when pierced with a fork. (Cooking time will vary because of the size of potato pieces and the types used.)
Drain the potatoes well. Return them to the hot pot and toss until the residual water is evaporated. Put them in a large bowl and pour the salad dressing over them while still very hot. If the salad dressing bottle is very large, don't use the whole thing--use just enough to have a little extra at the bottom of the bowl, but not enough to be soupy. The hot potatoes will absorb the excess as they cool.
Coarsely chop the parsley and toss all of it gently into the hot potato mixture.
Let the mixture come to room temperature, tossing occasionally to ensure the dressing coats all pieces evenly. Finish with cracked pepper and salt if needed.