In a medium skillet, heat 1 tablespoon of olive oil over medium heat. Add the finely chopped onion and sauté until soft and caramelized, about 10-12 minutes. Stir in the minced garlic for the last 2 minutes of cooking, then remove from heat and allow to cool slightly.
In a large mixing bowl, combine the ground beef, ground pork (if using), breadcrumbs, grated Parmesan, egg, dried thyme, salt, black pepper, and the cooled onion-garlic mixture. Mix gently until just combined.
Preheat your oven to 400°F (200°C). Shape the mixture into meatballs approximately 1 inch in diameter and place them on a baking sheet lined with parchment paper.
Transfer the baking sheet to the preheated oven and bake the meatballs for 20-25 minutes, or until fully cooked through and browned.
While the meatballs are baking, return to the skillet used for the onions. Pour in the beef broth and add the balsamic vinegar. Bring to a gentle simmer and reduce slightly for about 5-7 minutes.
Once the meatballs are baked, transfer them into the skillet with the sauce, gently coating each meatball. Let them simmer together for an additional 5 minutes.
Arrange the meatballs on a serving platter, drizzling the sauce over them. Garnish with freshly chopped parsley.
Notes
Serve with crusty bread or creamy mashed potatoes for a complete meal experience.
Keyword beef, French onion, meatballs, pork, savory