1. Preheat the oven to 350°F (175°C).

2. Cube the sourdough bread into bite-sized pieces and spread them out on a baking sheet.

3. Drizzle a small amount of oil over the bread cubes and toss them gently to coat evenly.

4. Roast the bread in the oven for 10-12 minutes, or until it becomes crispy and golden brown.

5. Let the bread cool completely on the baking sheet.

6. In a large pot, heat 2 tablespoons (30ml) of oil over medium heat.

7. Add the diced onion and sauté until softened, about 5 minutes.

8. Add the minced garlic and cook for an additional minute, stirring constantly to prevent burning.

9. Sprinkle 1-2 tablespoons (15-30g) of flour over the onion mixture and cook for 1-2 minutes, stirring constantly to prevent lumps.

10. Gradually pour in 2 cups (475ml) of warmed vegetable broth, whisking continuously to avoid lumps.

11. Bring the mixture to a boil, then reduce the heat to a simmer and cook for 5 minutes.

12. Add 1 can (14.5 oz or 410g) of crushed tomatoes, 1/4 cup (60g) of ajvar, and 1/2 cup (120ml) of heavy cream or half-and-half to the pot.

13. Stir well to combine all the ingredients.

14. Season the soup with salt and pepper to taste.

15. To assemble the soup, place a few roasted bread cubes at the bottom of a bowl.

16. Ladle the hot soup over the bread, then top with additional croutons and a sprinkle of fresh basil or parsley, if desired.

17. Serve the soup immediately and enjoy!