Heat a Dutch oven or other large pot over medium heat and add the olive oil. Cook the onion until translucent and tender, about 5 minutes. Add the garlic and chorizo; cook until chorizo is crumbled and cooked through, about 6 minutes. Stir in the beer, scraping browned bits from bottom of the pot; add the mussels. Steam the mussels, covered, over high heat 2 minutes; stir in butter and salt to taste. Cover and cook until mussels open, about 2 minutes. Sprinkle with cilantro.
This recipe was provided by professional chefs and has been scaled down from a bulk recipe provided by a restaurant. The Food Network Kitchens chefs have not tested this recipe, in the proportions indicated, and therefore, we cannot make any representation as to the results.