MUSSELS IN LAGER

1/2 stick (1/4 cup) unsalted butter
1 medium onion, chopped (1 cup)
2 celery ribs, cut into 1/4-inch dice (1 cup)
1 cup drained canned diced tomatoes (from a 14- to 15-oz can)
3 garlic cloves, finely chopped
1 teaspoon chopped fresh thyme
1 Turkish or 1/2 California bay leaf
1/2 teaspoon salt
1/4 teaspoon black pepper
2 cups lager such as Harp (16 oz; pour beer slowly into measuring cup;
do not measure foam)
2 lb mussels (preferably cultivated), scrubbed well and beards removed
1 tablespoon Dijon mustard
2 tablespoons heavy cream
1/4 cup chopped fresh flat-leaf parsley

Accompaniment: crusty bread

Heat butter in a wide 5- to 6-quart heavy pot over moderately high heat
until foam subsides, then cook onion, celery, tomatoes, garlic, thyme,
bay leaf, salt, and pepper, stirring occasionally, until vegetables are
softened, about 4 minutes.

Add beer and bring just to a boil. Add mussels and cook, covered,
stirring occasionally, until mussels open wide, 4 to 6 minutes,
transferring them to a bowl as they open. (Discard any mussels that
remain unopened after 6 minutes.) Remove pot from heat. Stir together
mustard and cream in a small bowl, then add mixture along with parsley
to hot broth and whisk until combined. Discard bay leaf. Serve sauce
over mussels.

Makes 4 first-course or 2 main-course servings.