Heat a large, deep skillet over medium-high heat. Add the olive oil and chorizo and saute for about 2 minutes. Then the celery, garlic, tomatoes, fennel and onions, and saute until tender but not too soft, 5 to 8 minutes.
Add the mussels, and saute again until the mussels start to pop open. Add the clam juice and wine and cover the skillet. Steam the mussels until they open, 7 to 10 minutes. Remove any mussels that didn't open, and transfer the rest from the skillet to a serving bowl(s), leaving the liquid behind. Add the butter and simmer until the liquid reduces a bit, about 2 minutes.
Pour the liquid over the mussels and serve with a delightful crusty bread.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.