Preheat oven to 180°C (350°F). Slice the tops off the tomatoes and set aside as lids. Using a spoon, carefully scoop out the tomato pulp into a bowl, leaving a sturdy shell. Reserve the pulp and chop finely.

Lightly salt the inside of each hollowed tomato and place them upside down on paper towels for 10 minutes to drain excess moisture.

Heat 3 tablespoons of olive oil in a large pan over medium heat. Sauté the diced onion for 5 minutes until softened. Add the garlic and cook for 1 minute until fragrant.

Add the rice to the pan and stir for 2 minutes to lightly toast. Pour in the reserved chopped tomato pulp and half of the canned crushed tomatoes. Season with salt, pepper, cinnamon, allspice, and oregano.

Stir in the fresh dill, mint, parsley, spring onions, and sugar. Remove from heat and let the mixture cool slightly for 5 minutes.

Arrange the hollowed tomatoes in a baking dish. Spoon the rice mixture into each tomato, filling them about three-quarters full to allow the rice to expand. Place the reserved tomato lids on top.

Mix the remaining crushed tomatoes with the water and remaining olive oil. Pour this sauce around the tomatoes in the baking dish.

Cover the dish tightly with aluminum foil and bake for 45 minutes. Remove the foil and bake for an additional 15 minutes until the tomatoes are tender and the tops are slightly caramelized.

Let the gemista rest for 10 minutes before serving. Serve warm or at room temperature, spooning the pan juices over each portion.