Saute the onion and garlic in olive oil then add the carrot and celery and cook for a few minutes.
Add the red lentil and ras el hanout (Moroccan spice mix) and stir to combine.
Add the diced tomatoes and preserved lemons. Check the complete recipe for substitutions if you don't have preserved lemons.
Add in the water or vegetable stock and cook for 20 minutes until the lentils are fully cooked.
Using an immersion blender or a regular one, blend the soup until smooth and creamy.