Rinse fresh blue mussels in a colander under tap water.

Set aside for a few minutes.

Tap any open mussels; discard those that don't close.

Add butter to a pot.

Cook chopped onion and celery with salt and pepper, stirring occasionally, until softened (about 5 minutes).

Add the beer and fresh mussels.

Cover and steam over high heat until the mussels are open (6-8 minutes).

Squeeze lemon juice over the mussels.

Add parsley.

Pour into a large bowl to share.