Peel and chop the potatoes into chunks.
Bring a pot of water to a boil. Add the potatoes and cook until fork-tender, about 15 minutes.
Drain the potatoes well and transfer them to a mixing bowl.
Mash thoroughly using a fork or potato masher.
Add cornstarch, salt, pepper, and onion or garlic powder. Mix until combined, then knead into a smooth dough.
Roll the mixture into equal-sized balls.
Heat neutral oil in a deep pan or skillet over medium heat.
Fry the potato balls for 2–3 minutes per side until golden and crispy.
Remove and drain on paper towels. Serve warm.