Heat the oil in a shallow covered casserole (will need the cover later), Spanish earthenware is recommended.

Saute onion and garlic until the onion is wilted.

Stir in the flour and cook 1 minute.

Add in the wine, bay leaf, lemon juice, pepper, and a little salt.

Simmer, covered, for 5 minutes.

Add the mussels to the sauce, cover, and cook until the mussels have opened.

Sprinkle with parsley and serve.