Peel and cube the Yukon Gold potatoes. Place them in a pot of cold salted water and bring to a boil. Cook for 15-20 minutes until tender. Drain and mash with milk, butter, scallions, dill, and salt until smooth.

In a skillet, heat olive oil over medium heat. Sauté cabbage for about 10 minutes until soft. Add garlic and cook for another 1-2 minutes, seasoning with salt.

Fold the sautéed cabbage into the mashed potatoes. Chill this mixture in the refrigerator for at least 1 hour.

Prepare the dipping sauce by mixing sour cream, mayonnaise, lemon juice, zest, parsley, and dill. Chill until ready to serve.

Form the potato mixture into balls, placing a cube of mozzarella in each. Ensure the cheese is completely enclosed.

Set up a breading station with flour, beaten eggs, and a breadcrumb mixture. Coat each ball in flour, egg, and breadcrumbs.

Heat oil in a frying pan to 300°F. Fry the balls in batches for 3-4 minutes until golden brown. Drain on paper towels.