I would like you to take a moment to admire my photo. See how it isn't blurry? All hail Joe, who clued me into the macro button on my digital camera! Thanks again, Joe.
And now that we can get up close and personal with the food, you can take another moment with me to wonder why this dish is referred to as "gratin". According to Wikipedia,
Gratin adapted from French cuisine is a type of casserole dish that is covered with Béchamel sauce or Mornay sauce, topped with buttered breadcrumbs or grated cheese and either baked or broiled, then served in its baking dish with a golden crust. Cooking au gratin is a technique rather than exclusively a preparation of potatoes (which is specifically a gratin dauphinois): anything that can be sliced thin, layered with a cream sauce and baked is material for a gratin: fennel, leeks, crabmeat, celeriac, aubergines.
And you can see from the photo that these mussels, tasty as they are with the tomatoes, basil, garlic and toastettes, are far from being bound together with a sauce of any kind. The half cups of creme fraiche and Parmesan cheese it calls for really get lost in the juice from the tomatoes--so they add a little flavor, but not much else.
I halved this recipe, and used cherry instead of plum tomatoes but other than that obeyed the letter of the law. It's a delicious, light summer meal, so if you're wondering how to cook those inscrutable netted bundles of shellfish in the corner of the fish case, give this one a try.
Folks, stay tuned for my next post--I'm grilling something tonight that is a first for me--octopus. I'm already filled with wonder.