In a large mixing bowl, combine cooled mashed potatoes, all-purpose flour, salt, and melted butter. Stir until a soft dough forms, about 3-5 minutes.

Lightly flour a clean surface and turn out the dough. Knead gently for 1-2 minutes until smooth and elastic.

Roll the dough into a circle about 1/4 inch thick and cut into quarters, forming triangular farls.

Heat a non-stick skillet over medium heat for about 3 minutes. Cook each farl for 3-4 minutes until golden brown, then flip.

Remove farls from the skillet and serve warm with butter, eggs, or preferred toppings.