Mussel Soup with Avocado, Tomato, and Dill

Ingredients

• 8 ounce avocado 
• 3 tablespoons optional: dill fresh coarsely chopped
• 12 inch thyme sprigs fresh
• 0.3 teaspoon pepper white
• 1 cup half and half 
• 12 ounce lager 
• 1.5 pounds leek white green sliced quartered (3 medium; and pale parts only)
• 3 pounds mussels scrubbed well (preferably cultivated)
• 0.3 pound pears halved
• 0.3 teaspoon salt 
• 2 tablespoons butter unsalted
• 1.5 cups water 

Equipment

• bowl
• paper towels
• sauce pan
• pot
• sieve
• plastic wrap
• cheesecloth

Directions

1. Wash leeks in a bowl of cold water, agitating them, then lift out leeks and pat dry.
2. Cook leeks in butter in a wide 5-quart heavy pot over moderate heat, stirring occasionally, until softened, 5 to 7 minutes.
3. Add thyme and cook, stirring, 1 minute. Stir in beer and water, then increase heat to moderately high and bring to a boil.
4. Add mussels and return liquid to a boil, partially covered. Cook, completely covered, stirring occasionally, just until mussels open wide, checking frequently after 4 minutes and transferring to a large bowl. (Discard any mussels that remain unopened after 8 minutes.)
5. Working over a bowl, remove mussels from shells and put in bowl (discard shells along with any clinging leeks).
6. Pour any cooking liquid accumulated in bowl back into pot.
7. Pour cooking liquid through a sieve lined with a double layer of cheesecloth or dampened paper towels into a 2-quart heavy saucepan. Stir in half-and-half, salt, and white pepper, then heat over moderately low heat until hot (do not let boil). Stir in mussels and heat until just warmed through.
8. Meanwhile, halve avocado, then peel 1 half (wrap remaining half tightly in plastic wrap and reserve for another use).
9. Cut into 1/2-inch cubes, then toss gently with tomatoes and dill in a bowl.
10. Divide soup among 6 shallow bowls and spoon some avocado mixture into each.
11. Serve immediately.
12. Soup, without half-and-half, can be made 1 day ahead and cooled completely, uncovered, then chilled (with shelled mussels in soup), covered.
13. Remove mussels and reheat soup over moderately low heat before adding half-and-half and then proceeding with recipe.