This recipe uses up leftover mashed potatoes and any leftover beef roast that would be too tough to eat when reheated. If you happen to have pulled pork or braised beef, that's even better!If you have leftover roast, place the slices in a food processor and chop coarsely.Mix all ingredients in a large bowl. Form into four balls and lightly flatten into patties. Place on a parchment and chill for 30 min in the fridge.For the breading:Place flour in a shallow pan, and breadcrumbs in another separate shallow pan.Beat eggs in a bowl.Carefully place the patties into flour mixture. Lightly pat both sides to dust off any flour clumps.Dredge in egg. Shake off excess. Place in breadcrumb mixture and coat evenly. Repeat for all patties.Pan fry in oil on medium heat and cook until golden brown on each side.