Heat the oil in a saucepan over medium-high heat. Add the onion. Cook about 4 min. Add the garlic, paprika powder, turmeric, cumin, cayenne pepper, cinnamon. Cook about 30 s.
Add the tomatoes, sweet potato, lentils, broth. Cover the pot and bring to the boil. Reduce the heat to low and simmer for about 12 min.
Add the chickpeas, coriander or parsley, season with salt, black pepper, drizzle with lemon juice. If needed, add more seasoning. Cover the pot and let the soup sit about 5 min.