I always add a little bit of sherry and it makes it so much better! I also like to spice it up and make a habanero salsa (just lime juice, chopped onion and chopped habaneros) to go on top (optional of course). If someone you know is allergic to bivalves, you should just substitute seafood stock in place of the clam juice and sub calamari instead of the mussels. It still works amazingly!
I like this soup very much. My partner had never tried mussels before, and had only tried shrimp a few times in his life. He was impressed with the taste of the seafood as well as the spiciness of the soup. I love the cilantro garnish. It makes a huge difference. I made few adjustments- I did have to use diced tomatoes which have larger chunks, but we liked them. I also could not find the whole spices to roast, so I substituted ground spices. This soup makes a lovely presentation and is pretty simple to make.