I might give you a different answer in the middle of February, when there’s nothing better than a hot bowl of mussels, swimming in some kind of garlicky, winey broth, but this time of year, chilled and marinated are my favorite way to go.
You can dress these anyway you want, but no matter how you flavor them, you’ll want to follow the same basic technique. By cooking the mussels with a minimum of moisture, and then reducing the liquids for the base of our marinade, we get an even more intense flavor, as well as an extra little kick of salinity.
By the way, I completely forgot to strain the cooking liquids before making the dressing, which can mean some grit, or tiny pieces of shell getting into your final product, so after everything is reduced, press the onion and juices through a mesh strainer before proceeding.
Most mussels sold at the grocery store are fairly well cleaned, but if yours aren’t, be sure to scrub well, and remove any beards. To ensure top quality, depending on proximity to the store, you can cook a couple when you get home, chill them, and then give them a test taste.
Mussels should have a fresh, sweet, mild, tastes-like-the-ocean flavor, and if yours don’t, or are gritty, or odd in any way, simply take them back, and get a refund. Anyway, that’s the worst-case scenario. The best-case scenario is what you see here, and I really do hope you give thesea try soon. Enjoy!