In a medium bowl, mix together 2 tablespoons olive oil, paprika, oregano, and salt and pepper. Stir in chicken pieces to coat. Cover, and refrigerate for at least 30 minutes.
In a 15-inch or 18-inch paella pan, heat olive oil and cook the chicken and chorizo over moderate heat. Break up chorizo with a spoon, until some of the fat is rendered and the chorizo is browned, 4 minutes.
Move the chicken and chorizo to one side of the pan. Add 2 tbsp of olive oil, plus the red pepper, onion and garlic to the other side of the pan and stir together cook over low heat, stirring, until the garlic and onions are softened and just beginning to brown, 5-6 minutes.
Stir in the tomatoes, rice, saffron and the 1 ½ cups of chicken stock. Season with salt and pepper and bring to a boil. Cover and simmer over low heat, without stirring, until the rice is al dente and the liquid is absorbed, 15 minutes.
Season the shrimp with salt and pepper. Turn down the heat on the pan, then add the dry white wine, lemon juice, shrimp, and mussels to the pan, cover, and cook for another 10 minutes or so, just until the mussels open up.
Garnish with parsley and lemon, drizzle with the remaining 1 tablespoon of olive oil and serve.
Notes
Keep any leftover seafood paella refrigerated in an airtight container for up to three days. I do not recommend freezing seafood paella, as the cooked mussels do not freeze well and would not reheat well. If you want to freeze a portion of this paella, remove the mussels before transferring to a freezer-safe airtight container.If you do not have a paella pan, you can use an aluminum or stainless steel skillet. While I love cast iron skillets, they are NOT good for making paella.