1. Heat olive oil in a large pot over medium heat.
2. Add diced onions, garlic, carrots, and celery. Sauté until softened, about 5 minutes.
3. Stir in cumin, paprika, turmeric, and black pepper. Cook for another minute until fragrant.
4. Add lentils, diced tomatoes, and vegetable broth. Bring to a boil.
5. Reduce the heat, cover, and let it simmer for 25-30 minutes until the lentils are tender.
6. Season with salt and lemon juice. Stir well.
7. Serve warm, garnished with fresh parsley.