Cut the tops and bottoms off the large yellow onions, carefully peel them without breaking the layers.

Make a slit along one side of each onion and place them in salted boiling water. Simmer for 10-15 minutes until softened. Reserve broth.

In a skillet, heat olive oil over medium heat, add chopped onion, sauté until softened, about 5 minutes.

Stir in minced garlic and cook for 1-2 minutes. Add ground beef, cook until browned, season, and mix in pureed tomatoes.

Add arborio rice and stir well. Pour in reserved onion broth and mix in parsley, oregano, dill, and mint. Stir on low heat for 10 minutes.

Gently stuff each onion layer with the filling, ensuring not to overload, and keep seam side down.

Arrange stuffed onions seam-side down in a baking dish; preheat oven to 400°F (200°C).

Combine additional pureed tomatoes, balsamic vinegar, and remaining onion broth. Cover stuffed onions with the sauce.

Cover and bake for 45 minutes, then remove foil and bake for 35-45 more minutes until tender.

Allow to cool slightly before serving. Sprinkle with parsley and enjoy with Greek yogurt and crusty bread.