Combine the tomato sauce, red wine, brown sugar, garlic, lemon juice and 1 teaspoon salt in a large saucepan. Give it a good stir, bring it to simmer over medium-low heat and simmer, uncovered and stirring occasionally, until thickened, about 20 minutes.
Preheat the oven to 500 degrees F. Spray 2 baking sheets with nonstick cooking spray.
Combine the ground pork, beef, onion, egg, shredded potato and remaining 2 teaspoons salt in a large bowl. Gently mix together to incorporate all the ingredients. Portion out the meatballs using a tablespoon measure or small scoop. Shape into small balls about 1 inch in diameter and place on the prepared baking sheets evenly spaced out, about 20 per baking sheet. Bake until lightly browned, about 5 minutes.
Combine the cooked meatballs with the sauce and simmer for 30 minutes. (Or, in a 4-quart slow cooker, combine the sauce and cooked meatballs and cook on high for 2 hours.)
For easy clean up, line your baking sheets with foil.