01 - Heat olive oil in a large soup pot over medium-low heat. Add sliced onions with a pinch of salt. Cook, stirring occasionally, for 20-25 minutes until onions are deeply golden and caramelized.
02 - Add garlic, carrots, and celery to the pot. Sauté for 3-4 minutes until vegetables are slightly softened.
03 - Stir in cumin, smoked paprika, black pepper, thyme, and bay leaf. Cook for 1 minute until spices become fragrant.
04 - Add rinsed red lentils and vegetable broth. Bring to a boil, then reduce heat to maintain a simmer. Cook uncovered for 15-20 minutes until lentils and vegetables are completely tender.
05 - Remove bay leaf from the pot. Use an immersion blender to partially or fully blend the soup according to your preferred consistency.
06 - Taste and adjust salt and pepper as needed. Serve hot, garnished with fresh parsley and a squeeze of lemon juice if desired.