Mussels in white wine with tomatoes and celery

Bring the white wine to the boil in a saucepan with an equal amount of water, add the mussels, cover and cook until all the mussels have opened (approx 10 minutes), shaking gently from time to time.  Add the butter, remove from the heat and then add the celery and tomatoes. Drizzle over some lemon juice and serve with toast.