| 1 | Bring two cups water, white wine and fresh thyme sprigs to boil in large pot. |
| 2 | Add mussels, cover and boil until opened, about 4 minutes. |
| 3 | Using slotted spoon, transfer mussels to bowl. |
| 4 | Discardy any unopened mussels. |
| 5 | Strain and reserve cooking liquid. |
| 6 | Remove meat from shells and reserve. |
| 7 | Discard shells. |
| 8 | melt butter in heavy large saucepan over medium heat. |
| 9 | Add leeks and saute" until just tender, about 4 minutes. |
| 10 | Mix in potatoes and reserved mussel cooking liquid. |
| 11 | Cover and cook until potatoes are tender, about 35 minutes. |
| 12 | Transfer leek-potato mixture to food processor. |
| 13 | Add clam juice and puree until smooth. |
| 14 | (can be prepared 1 day ahead. |
| 15 | Cover mussels and soup separately and then refrigerate). |
| 16 | return soup to heavy large saucepan and bring to simmer. |
| 17 | Stir in half and half and reserved mussels. |
| 18 | Cook until just heated through. |
| 19 | Season to taste with salt and pepper. |
| 20 | Mix in chopped herbs and serve. |
