In a large pot, combine your olive oil, diced onion, and salt. Place the pot over medium-low heat and cook for 5 to 10 minutes, or until the onion turns translucent and browns slightly. **** see notes
Add the coriander and garlic to the pot, and cook for another minute or so. This is just to slightly toast the garlic and coriander.
Add the carrots, lentils, and water to the pot. Raise your heat to high and bring the soup up to a boil. Reduce heat to medium-low and simmer the soup for 15 minutes. Add the spinach and continue simmering for another 15 to 20 minutes, or until the lentils are cooked through and the vegetables are softened.
If you find the soup is too thick, add a splash of water to thin your soup to your liking. Taste for seasoning and adjust if needed. (Optional) Add a squeeze of lemon juice at the end to brighten up the soup!