In a large sauté pan, heat the oil on medium-high and cook the onions for 2-3 minutes. Add carrots, garlic, oil, cumin, turmeric, cinnamon and pepper; cook for another 2-3 minutes. Add broth, water, cauliflower, cooked lentils, tomatoes and tomato paste, and stir until well combined.
Heat to a boil; turn down to simmer and cook, covered, for 30 minutes.
Just before serving, stir in spinach, cilantro and lemon juice. Cook for 5 minutes.
Refrigerate up to 3 days, or freeze for up to 6 months.