1. Preheat the oven to 425 degrees.
2. In a large bowl, combine the tomatoes, onion, garlic cloves, and fresh herbs. Add the olive oil, sugar, salt and pepper, tossing to coat the ingredients well.
3. Pour ingredients out onto a parchment lined baking sheet. Place each tomato half face down on the baking sheet.
4. Roast the tomatoes in the oven until broken down and caramelized, approximately 30 minutes.
5. Remove the baking sheet from the oven. Remove the herb sprigs.
6. Carefully pour the baking sheet contents into a 3+ quart saucepan.
7. Place saucepan on stovetop over medium heat. Add the vegetable stock and lemon juice. Stir well.
8. Using an immersion blender, purée the soup until smooth.
9. Allow soup to come to a low boil, and cook for 7-8 minutes, until heated throughout.
10. Remove from the heat and cool slightly. Season for salt, pepper, and heat.
11. Garnish soup with fresh basil and other desired toppings.