Prepare the mixture: Add the cold mashed potatoes, egg, flour, salt, and pepper to a mixing bowl. Stir until everything is fully combined.(Cold potatoes hold shape better.)
Add optional ingredients: Fold in cheese, herbs, or any extras. Avoid adding too many wet ingredients (they make the mixture loose).
Shape the patties: Scoop a handful of the mixture and press it into small patties, about ½ inch thick.If the mixture feels too soft, add 1–2 teaspoons more flour.
Heat the skillet: Pour oil into a skillet and heat over medium-high.The oil should lightly shimmer but not smoke.
Fry the patties: Carefully place the patties in the skillet. Cook 3–4 minutes per side until golden brown and crispy.Avoid flipping too early — let the crust form.
Drain and season: Transfer patties onto paper towels and sprinkle a little extra salt while hot.
Serve immediately: Enjoy with sour cream, ketchup, spicy mayo, or a fried egg on top.
