01 - Set oven to 425°F (220°C).
02 - Halve red bell peppers, discard seeds and membranes, place cut side down on a parchment-lined baking sheet.
03 - Roast 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 pepper flesh.
04 - Heat olive oil in a large pot over medium heat. Add chopped onion, diced carrot, and celery; cook for 5 to 7 minutes until softened.
05 - Incorporate minced garlic, smoked paprika, ground cumin, and chili flakes; sauté for 1 minute to release aromas.
06 - Stir in roasted red peppers and rinsed lentils, then pour in vegetable broth.
07 - Bring to a boil, reduce heat, and simmer uncovered for 20 to 25 minutes until lentils are tender.
08 - Purée soup using an immersion blender or in batches with a countertop blender until smooth; leave slightly chunky if preferred.
09 - Add salt and freshly ground black pepper to desired preference.
10 - Ladle into bowls, garnish with chopped fresh parsley and a squeeze of lemon juice.