Heat oil in a large, heavy stockpot over medium heat. Add shallot; cook, stirring occasionaly, until soft, about 3 min. Add garlic and red-pepper flakes; cook, stirring occasionally, 3 min.

Add wine, bring to a boil. Add tomatoes and chorizo. Reduce heat, and simmer, stirring occasionally, 15 min. Season with salt + pepper.

Add mussels. Cover, and continue to coo, shaking pot occasionally, until mussels open, about 10 min (discard unopened ones). Add parsley, toss. Serve immediately.