Soak the mussels in cold water for 30 minutes – 1 hour before cooking. Then drain and set aside for cooking.
Set a pot on medium heat. Once hot, add butter and white wine and bring to a simmer. Add mussels then cover and steam for 5 – 8 minutes, or until the shells begin to pop open. Note: if the mussel is open BEFORE steaming, then I recommend tossing it. Then set the pot aside.
Place a large (Dutch oven) pot on medium heat, then add olive oil and onions. Sautée for 3-5 minutes then add garlic and cook for another 2 minutes. Add white wine and allow the onions to be reduced by half.
Add the rest of the seasonings and stir to mix well. Add the bay leaves, bring to a gentle simmer, then cover the pot and cook for 20 minutes.
After 20 minutes, add the seafood to the soup – mussels, sea bass and shrimp – then reduce the heat and cook for an additional 10 minutes on low heat.
Remove from the heat, then garnish and enjoy!