1. Heat the olive oil in a large pot or Dutch oven over medium heat. Add the chopped onion and cook, stirring occasionally, until it softens and becomes translucent, about 5-7 minutes.

2. Add the minced garlic to the pot and cook for another 1-2 minutes, stirring constantly. Be careful not to let the garlic brown, as it can become bitter. It should be fragrant and lightly golden.

3. Pour in the vegetable broth and add the dried thyme. Bring the mixture to a gentle simmer, then reduce the heat to low, cover, and let it cook for about 10 minutes to allow the flavors to meld.

4. Stir in the cubed sourdough bread. Allow it to simmer for another 5 minutes, letting the bread soften and begin to break down in the broth. Then, pour in the heavy cream and stir well to combine.

5. Carefully transfer the soup in batches to a blender (or use an immersion blender directly in the pot). Blend until the soup is completely smooth and creamy. If using a regular blender, make sure to vent the lid to allow steam to escape and avoid pressure buildup. Return the blended soup to the pot.

6. Stir in the fresh lemon juice. Season the soup with salt and black pepper to taste. Start with the recommended amounts and add more if needed. The soup should have a bright, tangy finish from the lemon.

7. Ladle the hot soup into bowls. Garnish with fresh chopped parsley and a lemon slice, if desired, for a pop of color and extra freshness. Serve immediately and enjoy!