Preheat your oven to 200°C (390°F). Prepare a baking sheet with parchment paper.
Scrub or peel the carrots, then cut them into thick rounds. Toss them with olive oil, a pinch of salt, and smoked paprika until evenly coated.
Spread the carrots on the baking sheet in an even layer. Roast for 25-30 minutes, shaking the pan halfway through, until edges are caramelized and fragrant.
While the carrots roast, heat a tablespoon of olive oil in a large pot over medium heat. Add chopped onions and cook for 5-7 minutes, stirring occasionally, until soft and golden.
Add minced garlic to the aromatics and cook for another minute until fragrant.
Stir in the rinsed red lentils, then pour in the vegetable broth. Bring to a gentle boil, then lower the heat to simmer, covered, for about 20 minutes until the lentils are tender and starting to break down.
Once the carrots are roasted and slightly cooled, add them to the pot. Use an immersion blender or transfer to a blender to purée until silky and smooth.
If the soup is too thick, stir in a little more broth or water to reach your desired consistency. Taste and season with salt, pepper, and a squeeze of lemon juice.
Finish by drizzling with a splash of olive oil and garnishing with fresh herbs if desired. Serve hot, enjoying the velvety texture and smoky aroma.