Begin by peeling and dicing about 4 large russet potatoes. Place them into a pot and cover with salted water, bringing it to a boil. Cook for approximately 15 minutes until they are fork-tender. Drain the potatoes, then mash them while still warm, incorporating salt and heavy cream to create a thick, creamy consistency.

In a skillet, heat a tablespoon of avocado oil over medium heat. Add finely diced scallions and campari tomatoes, sautéing until they are caramelized, around 5-7 minutes. Then, stir in 1 pound of ground beef along with ground cumin and cook until the beef is browned and fully cooked, which should take about 8-10 minutes. Remember to season with salt to taste.

Once your mashed potatoes and filling are ready, divide the potato mixture into equal portions, shaping them into discs in your hands. Place about 2 tablespoons of the beef mixture in the center of each disc, then carefully fold the edges over to create a ball, ensuring there are no openings.

In a medium bowl, whisk together half a cup of flour, one cup of heavy cream, and two eggs until you have a smooth, thick batter. Prepare a bowl of panko crumbs nearby for optional coating.

Heat enough avocado oil in a fryer or deep skillet to fully submerge the stuffed potato balls, approximately 350°F (175°C). Fry the papas rellenas in batches for about 8-10 minutes, or until they turn golden brown and crispy.

Once your Beef Stuffed Potatoes are cooked to perfection, garnish with freshly chopped parsley and serve hot.