Peel the onions. Carefully slice off the very top (stem end) and a small portion of the root end, just enough to make them stable. Using a sharp knife or a spoon, gently core out the center of each onion, leaving about 2-3 outer layers intact. Be careful not to pierce through the outer layers. Finely chop about 1/2 cup of the reserved inner onion flesh for the stuffing; set aside the rest for another use or discard.

In a large pot, bring about 8 cups of water with 1 teaspoon of salt to a boil. Carefully place the hollowed onions into the boiling water and blanch for 10-15 minutes, or until they are slightly tender but still hold their shape. This step helps soften them for stuffing and removes some of their raw bite. Drain the onions and let them cool completely on a clean kitchen towel, open-side down, to remove excess water.

While the onions are cooling, heat 1 tablespoon of olive oil in a large skillet over medium heat. Add the 1/2 cup of finely chopped reserved onion flesh and sauté for 3-5 minutes until softened and translucent. Add the ground beef and cook, breaking it up with a spoon, until browned. Drain any excess fat.

Remove the skillet from heat. Stir in the rinsed short-grain rice, chopped fresh parsley, chopped fresh mint, dried oregano, ground cumin, ground cinnamon, salt, black pepper, tomato paste, and 2 tablespoons of water. Mix everything thoroughly until well combined.

Preheat your oven to 375°F (190°C).

Once the blanched onions are cool enough to handle, gently fill each onion cavity with the meat and rice mixture. Pack it snugly but do not overstuff, as the rice will expand during cooking. You may have some stuffing left over, which can be baked alongside the onions or used in other dishes.

In a medium saucepan, heat 1 tablespoon of olive oil over medium heat. Add the minced garlic and sauté for 30 seconds until fragrant. Pour in the crushed tomatoes, vegetable or beef broth, and sugar. Season with salt and pepper to taste. Bring the sauce to a gentle simmer, then remove from heat.

Pour about half of the prepared tomato sauce into the bottom of a 9x13 inch baking dish. Carefully arrange the stuffed onions in a single layer in the dish. Pour the remaining sauce over and around the stuffed onions.

Cover the baking dish tightly with aluminum foil. Bake for 60-75 minutes, or until the onions are very tender and the rice inside is fully cooked. To check for doneness, you can carefully remove one onion and check the rice. For a slightly caramelized top, you can remove the foil for the last 15 minutes of baking.

Carefully remove the baking dish from the oven. Let the stuffed onions rest for 5-10 minutes before serving. Serve hot, spooning extra sauce from the dish over each onion.