In a large bowl, thoroughly mix the softened butter, tomato paste, and cayenne together until uniform in color. Lay the butter mixture onto a piece of plastic wrap and form it into a log. Wrap the butter log in the plastic wrap and put it in the fridge.

Heat a drizzle of olive oil in a stockpot over medium-high heat. Add garlic and let it cook for a minute. Add the vermouth and mussels. Cover and let mussels steam for about 3 minutes.

Remove the open mussels from the pot and set aside. If some are still closed, let them cook for a couple minutes longer. If they remain closed, discard them. Once all the mussels are out of the pot, let the liquid reduce for a minute. Reduce the heat and stir in the parsley and 3 tablespoons butter mixture.

Spoon the mussels back into the pot and gently mix to coat with broth. Divide the mussels and broth into two bowls and serve with bread.

Recipe courtesy of Abby Rogerson at Washington Sea Grant.