Wash the leek and cut into thin rings. Peel and chop the shallots. Wash parsley and thyme and shake dry. Wash and clean the mussels
Heat the fat in a saucepan. Sauté the leek and shallots for about 4 minutes. Add mussels, thyme and parsley, deglaze with wine and about 100 ml water. Cover and simmer for about 8 minutes until the mussels have opened. Pour the mussels into a sieve and collect the stock. Discard unopened mussels. Remove herb stalks. Keep mussels and vegetables warm
Wash the chives, shake dry and cut into small rolls, except for about the upper third for garnishing. Bring the cooking stock and cream to the boil in a saucepan. Stir starch and 2 tbsp. water until smooth, thicken sauce with it. Let sauce simmer for 2-3 minutes, season with salt and pepper. Add chive rolls. Arrange mussels on plates and pour the sauce over them. Garnish with chives