Scrub the mussels and remove beards, if necessary, and set aside in a large bowl.
In a large deep skillet or stock pot, heat the olive oil over med-high heat and add the chorizo. Cook the chorizo until golden and seared on all sides and transfer to a dish using a slotted spoon. Add the onion to the pan and sauté until softened, approximately 4 minutes. Add the garlic and corn cooking until the corn starts to brown. Pour in the beer and scrape up the brown bits on the bottom of the pan. Stir in the lime juice and butter bringing the mixture to a boil.
Add the mussels to the pan and cover with a lid. Steam the mussels until all the shells have opened, approximately 5 minutes...do NOT overcook. Remove the lid and sprinkle with cilantro. Serve immediately.