Rinse mussels with cold water in a colander until the grit washes away. No need to soak the mussels.
Heat olive oil in a large Dutch oven or pot over medium heat. Add chorizo and onions and cook until chorizo is well-browned and onions soften.
Add tomato paste, cumin, oregano, smoked paprika, cayenne and garlic and stir frequently for two minutes.
Pour in the pilsner, diced tomatoes and chicken stock and stir to combine to make the chorizo-tomato sauce for steaming the mussels.
Add mussels and cover for two minutes. Uncover and stir mussels. Cover mussels again and steam for another three minutes. Mussels are done when they open.
When you need an elegant yet simple appetizer, it doesn’t get more perfect than these steamed beer mussels with chorizo and tomatoes. And don’t forget the bread.