Peel and roughly chop garlic. Put parsley tips aside for garnishing, remove remaining leaves from stems and chop finely. Zest lemon peel and squeeze juice.
Heat 4 tbsp. of oil in a saucepan and sauté garlic and Ras el Hanout at medium heat for 20 seconds, stirring constantly.
Add 2 cups warm water, stock cube and lentils. Simmer for 15 minutes at medium heat.
Remove saucepan from heat and season with salt, some sugar and pepper to taste. Add two-thirds of the sour cream and puree the soup with a hand-held blender.
Serve lemon lentil soup in a deep dish and garnish with remaining sour cream and parsley tips.