Boil the potatoes. Peel and cut the potatoes into chunks. Place them in a pot of water and cook until soft, about 15–20 minutes. Drain well.

Prepare the onion and carrot mixture. In a skillet, heat a splash of olive oil over medium heat. Add the finely chopped onion and sauté until translucent. Add the grated carrot and cook for 3–4 minutes until slightly softened. Remove from heat.

Mash the potatoes. Transfer the drained potatoes to a large bowl and mash until smooth.

Season and mix. Add the onion-carrot mixture to the potatoes, along with the chopped parsley, salt, and black pepper. Mix until everything is well combined.

Shape the potato balls. Take a small portion of the potato mixture in your hand, flatten it slightly, and place a cube of mozzarella in the center. Enclose the cheese completely with potato mash, forming a ball. Repeat with the remaining mixture.

Prepare the batter. In a separate bowl, whisk together the eggs, sour cream (or yogurt), a pinch of salt, black pepper, and flour until smooth.

Fry the potato balls. Heat sunflower oil in a frying pan over medium heat. Dip each potato ball in the batter, coating it evenly, then place it in the hot oil. Fry on all sides until golden brown and crispy.

Drain and serve. Transfer the fried potato balls to a plate lined with paper towels to remove excess oil. Serve hot for maximum cheese pull satisfaction.