Prepare the MusselsScrub the mussels under cold running water and remove beards, if any. If using farm-raised mussels, they may not have beards and will be easier to clean. Discard any mussels that are cracked or damaged. If a mussel is open, tap it lightly—if it does not close, discard it.

Make the RouxMelt the butter in a large Dutch oven or heavy-bottomed saucepan over low heat. Stir in the flour and cook, stirring constantly, for 6 to 8 minutes, until the roux turns a light brown color.

Sauté the VegetablesAdd the onion, bell pepper, and celery to the roux. Stir well, cover, and cook over low heat for 6 to 8 minutes, stirring occasionally, until the vegetables are softened.

Boil the PastaMeanwhile, bring a large pot of salted water to a boil (use 1 teaspoon of salt per quart of water).

Prepare the SauceStir in the diced tomatoes (with their juice), tomato paste, clam juice (or chicken stock), lemon juice, cayenne pepper, black pepper, and oregano. Simmer the sauce uncovered, stirring occasionally, for about 15 minutes, or until thickened.

Cook the PastaAdd the linguine to the boiling water and cook according to package directions until al dente.

Cook the MusselsWhile the pasta is cooking, add the mussels to the sauce and stir. Cover and let simmer over low heat for 5 to 8 minutes, or until the mussels open.

Remove Unopened MusselsTransfer the opened mussels to a large bowl. Discard any mussels that did not open. Taste the sauce and adjust the seasoning with kosher or sea salt, if needed.

Assemble the DishDrain the pasta and divide it between two wide, shallow bowls. Arrange the mussels around the pasta and spoon the sauce generously over the top.

Serve and EnjoyServe immediately with a warm, crusty baguette for dipping. Enjoy!!