Preheat the oven to 300°F (148°C). Rinse the Roma tomatoes with water, drain, and pat dry with paper towels. Slice them in half and transfer them to a large bowl.
Add the olive oil, garlic, Italian seasoning, sugar, salt, ground black pepper, and oregano. Gently stir to combine well.
Transfer the tomatoes to a baking sheet or sheet pan, arranging them in a single layer. Slow roast the tomatoes for 1 hour. Remove from the oven and serve immediately.