Heat the olive oil in a large saucepan, then add the onion and saute for three to four minutes, until translucent. Add the garlic, leave it to soften slightly, then add the carrot. Stir everything together and saute for a minute or two.
Add the rinsed lentils and stir well – the mixture might clump, but keep stirring. Add the bouillon powder, cumin, ras el hanout and salt, and cook over a low heat, stirring occasionally, for 30 seconds. Add the coconut milk, 1.3 litres of cold water and the fresh coriander, and adjust the salt to taste. Cover the pan, bring to a simmer and cook on a medium-low heat for 20 minutes.
Half-blend the mixture with a stick blender to give it a creamy texture while keeping some chunks intact. If need be, add more water, and remember to check the salt. Simmer for another 15 minutes, then serve hot garnished with extra coriander and the lemon slices.