- Scrub the mussels and make sure all are closed or closes when knock on.
- Throw away mussels that doesn't close.
- Finely chop onion and celery, and add to a casserole with blue mussels and water.
- Cover with a lid and let steam for 3-4 minutes.
- Shake the casserole so the mussels in the bottom comes up.
- Sieve the broth into another casserole and add beer, parsley, thyme and bay leaf.
- Bring to a boil and cook until the gas from the beer is gone.
- Add butter and taste with salt and pepper.
- Pour the sauce over the blue mussel and serve with bread on the side.