Place the peeled, cooked potatoes in a large mixing bowl. Mash thoroughly until smooth and free from noticeable lumps.
Add the cornstarch, breadcrumbs, salt, black pepper, and chili powder. Work everything together until you have a soft dough that holds its shape without sticking excessively to your hands. Add a small amount of extra breadcrumbs if the mixture feels too wet.
Cover the potato mixture or place it in a sealed container. Refrigerate for 30 minutes to make the dough firmer and easier to shape.
Lightly grease your hands and work surface. Roll or gently press the chilled potato mixture to approximately ½ centimeter thick.
Cut the flattened dough into circles using a round cookie cutter. Gather any leftover scraps, reshape them, and continue cutting until the dough is used.
Lightly coat the end of a drinking straw with oil, then press it through each potato circle twice to form the eyes.
Create the smiling mouth by carefully pressing the curved edge of a spoon into each circle.
Heat enough cooking oil for frying in a deep pan over medium heat.
Carefully lower a few potato smileys into the hot oil without overcrowding the pan. Fry for approximately 3 to 4 minutes on each side, or until crisp and evenly golden.
Remove with a slotted spoon and transfer to a paper towel-lined plate to absorb excess oil.
Serve while warm and crispy with ketchup, garlic dip, spicy mayonnaise, or your favorite dipping sauce.