In a large saute pan, cook the chorizo until brown over medium-high heat, about 4 minutes. Remove with a slotted spoon and drain on paper towels. Drain off all but 1 tablespoon of fat from the pan.
Add the butter and when melted, add the onions, fennel, salt, and pepper, and cook, stirring, for 4 minutes. Add the garlic and tomatoes, and cook, stirring, for 1 minute. Add the wine, cream, and parsley, and bring to a boil. Add the mussels, cover, and cook until the shells have opened, about 4 minutes.
Remove from the heat and stir in the sausage. Discard any shells that do not open. Transfer to a deep bowl and serve immediately with hot French bread for dipping.
Yield: 4 appetizer servings