Prep. time: 5 minutes
Cooking time: 20 minutes

1. Brush and clean the mussels; place them in a saucepan with the chopped shallot and white wine. Cook, covered, stirring occasionally. 
2. Clean the leek, keeping only the white and pale green part; chop finely. 
3. Peel and dice the potatoes.  
4. Sweat the leek in butter, add the potato, the liquid from the mussels and the water. Cook gently. 
5. At the end of the cooking time, add the lamb's lettuce and cook for just 5 minutes. Purée. Correct the seasoning.
6. Shell the mussels. 
7. Serve  the soup in bowls, garnishing with the mussels. Garnish with a few lamb's lettuce leaves.