In the bowl of a stand mixer fitted with the paddle attachment, combine warm water, sugar, and yeast.Let yeast sit for 5-10 minutes, or until foamy.Stir in milk, oil, mashed potatoes, and eggs.Add salt and 3 cups flour. Stir to combine.Switch to dough hook.Continue adding flour, 1/4 cup at a time, until dough clings to to dough hook and clears the side of the bowl.Cover, and let sit until dough doubles in size, about 1-1 1/2 hours.Turn dough out onto floured surface.Shape into 24 rolls.Place rolls on a parchment-lined baking sheet.Cover, and let rise for 30 minutes.Toward the end of the rising time, preheat oven to 275 F.Bake rolls for about 20 minutes, or until set but not browned.Remove from oven, and let cool to room temperature.Place in freezer bag, and freeze until ready to use.When ready to finish baking the rolls, thaw in fridge overnight.Preheat oven to 400 F.Bake rolls for 7-10 minutes, or until golden brown.At this point, I brush them with melted butter before serving, but that's completely optional.