Reheat mashed potatoes until slightly warm (not hot; just enough that it's not too tough to stir). Add the sour cream and stir to combine, then add breadcrumbs and egg and stir again to combine.
Finally add the crumbled bacon and chopped parsley.
Form 2-inch balls from the mixture and place them on a baking pan with parchment paper.
Freeze for 1 hour or until solid.
Heat the vegetable oil in a large frying pan over medium heat to 350 °F (177 °C). The oil should fill the pan about 2 inches of the way up.
Leave the potato balls in the freezer while you fry 3-4 balls in the oil for 1-2 minutes on each side, or until they turn a golden color on all sides.
Remove them from the oil and place them on a plate with a paper towel to drain off the excess oil.
Repeat the frying process with the remaining potato balls taking out only as many as you need at a time from the freezer.
Serve with country white gravy, freshly chopped chives or ketchup.
Notes
These fried potato balls can be stored in an airtight container in the fridge for up to 3 days.Reheat them in an oven set to 350 degrees Fahrenheit for 5-6 minutes, or until toasty.