Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
- Place the chopped carrots, onion, tomatoes, cauliflower, red bell pepper, and garlic on the baking sheet. Drizzle with olive oil and toss to coat evenly. Sprinkle with dried thyme, rosemary, salt, and pepper.
- Roast the vegetables for 25-30 minutes, stirring halfway through, until they are tender and slightly caramelized.
- Transfer the roasted vegetables to a blender or food processor. Add vegetable broth and blend until smooth and creamy. If the soup is too thick, add more broth or water to reach your desired consistency.
- Pour the blended soup into a large pot and heat over medium-low for 5-10 minutes, allowing the flavors to meld. Taste and adjust seasoning as needed.
- Serve hot, drizzling with lemon juice (optional) for added freshness.