I love a good onion-topped, mushroom-y green bean casserole just as much as the next guy—even more than the next guy if it's 100% homemade from scratch—but most green beans in my home end up in the salad bowl, not the casserole dish. Why?
Because I love the tender-crisp crunch of a perfectly blanched green bean, shocked ice cold at just the right moment.* Because I love that sweet, grassy bite, more flavorful than your standard greens. Because using real vegetables turns from "oh, that's a salad," to "oh, hey, pass me that great looking side dish of green beans!" Because I like that the beans can be blanched and the dressing can be made the day ahead, requiring under a minute to assemble and serve when you've got other dishes to attend to and a turkey to carve.
*Despite what some recently published evidence from other sources might suggest, I've found shocking in cold water to be essential for the texture of perfectly blanched vegetables
The general rule of thumb for creating a great composed salad is to use as few ingredients as you need to create textural and flavor contrast. Usually one main ingredient, about 3 accent ingredients, and a good dressing is all you need. My own personal rules for creating a great composed salad would tack on another suggestion: Include something pickled or brined. Always include something pickled or brined.. Whether it's pickled red onions tossed in an arugula salad or some nice briny olives thrown into a chopped salad, it's those salty, tangy bursts of flavor that will have folks jumping back for more.
In this case, I went with homemade pickled banana peppers, which could just as easily be replaced with Italian-style jarred Peperoncini if you don't want to go the homemade route. (I suggest you do, as they're really great on pizza). Thinly sliced shallots add some sweetness and pungency to the mix, while toasted pinenuts offer their nutty crunch. Four ingredients. Done.
The dressing is only slightly more complicated. If you're the kind who doesn't care for anchovies, you're probably not the kind who will be coming to my Thanksgiving dinner. But never fear: any sort of creamy, savory, mayo-based dressing will work in this salad. I make mine by mashing anchovies to a paste and combining them with mayonnaise, parmesan, and Worcestershire with plenty of black pepper. It differs from my standard Caesar dressing only in its proportions, but it's those extra anchovies that really pull the thing together. You'd be hard pressed to find a more flavorful, refreshing side dish for your feast.