Meatballs: Lightly sauté the onion and garlic for the meatballs in a little oil until softened. Set aside to cool slightly. In a large bowl, combine the pork mince, sautéed onion and garlic, parsley, egg, breadcrumbs, soy sauce, salt, and pepper. Mix until just combined – take care not to overwork the mixture. Shape into evenly sized meatballs. Heat a little oil in a pan and brown the meatballs on all sides. Remove and set aside.
Marinara sauce: In the same pan, sauté the onion until softened. Add the garlic and cook for another minute. Stir in the chopped tomatoes, brown sugar, and balsamic vinegar. Simmer for 10-15 minutes until slightly thickened. Add the chopped basil and season to taste. If the sauce becomes too thick, add a splash of water. Return the meatballs to the sauce and simmer gently for 5-10 minutes until cooked through.
Polenta: Bring the water, milk, and salt to a boil in a large pot. Gradually whisk in the polenta, stirring constantly to prevent lumps. Reduce the heat and continue stirring for 15-20 minutes until thick, smooth, and creamy. Stir in the butter and Parmesan cheese just before serving. Taste and adjust seasoning if needed.
To serve: Spoon the polenta into bowls, top with meatballs and sauce, and finish with a spoonful of basil pesto and a generous sprinkle of Parmesan cheese.