Preheat the oven to 350°F/180°C, and line a half sheet pan with parchment paper for easy clean up.
Spread the carrot on the sheet pan, drizzle with 2 tablespoons of olive oil, and season with salt and pepper. Roast for 30-40 minutes flipping halfway through, until the carrots can be easily pierced with a fork. Mine took 35 minutes.
In a dutch oven or saucepan, heat the remaining olive oil and sauté the onion until soft and translucent. Add garlic, and cook for 30 seconds.
Add the coriander, cumin and paprika and cook for 30 more seconds.
Add the roasted carrots, and cover with vegetable stock or water. Over medium high heat, bring to a boil, reduce heat and simmer for 5 minutes.
Transfer the mixture to a blender, add lemon juice, and season with more salt if desired. Blend until smooth.
Serve immediately in bowls with croutons, and fresh herbs (I used basil).