I made this recipe without the celery and added in thinly sliced serrano peppers while the tomato and onions cooked. Then I threw on some fresh sliced peppers at the end. This was a hit. A very nice, deep, complex flavor with some kick. I like this recipe because of the tomato...I think it's what's missing in most of the other mussel recipes.
Very good and easy - served over linguini and it was very satisfying.