01 - Preheat oven to 425°F.
02 - Halve red bell peppers, remove seeds and membranes, and place cut side down on a baking sheet lined with parchment paper.
03 - Roast peppers for 20 to 25 minutes until skins are blistered and charred. Transfer to a bowl, cover with plastic wrap, and let steam for 10 minutes. Peel skins and chop flesh.
04 - Heat olive oil in a large pot over medium heat. Add onion, carrot, and celery; sauté for 5 to 7 minutes until softened.
05 - Add garlic, smoked paprika, cumin, and chili flakes; cook for 1 minute until fragrant.
06 - Add roasted pepper flesh and rinsed lentils to the pot. Pour in vegetable broth.
07 - Bring mixture to a boil, then reduce heat and simmer uncovered for 20 to 25 minutes until lentils are tender.
08 - Purée soup using an immersion blender or transfer to a countertop blender in batches until smooth or slightly chunky, as preferred.
09 - Season with salt and black pepper to taste.
10 - Serve hot, garnished with fresh parsley and a squeeze of lemon.