Beets: People either love them or hate them, and this can create a divide at the dinner table. Now, I can’t promise that any of your beet-averse family members or friends will do a complete 180-degree turn on their opinion when it comes to these earthy roots. I can suggest, however, that this gratin might be your best chance to convert them. Baby beets are mild and sweet, and their flavor is less assertive than their grown-up relatives. In this recipe, they are thinly sliced and blanketed in creamy layers of garlic, orange-infused sour cream, and nutty, piquant Gruyere cheese. If you must cloak a vegetable, this is the way to do it. Happily, all the flavors meld together, and while the beets are undeniably present, they are not overwhelming in flavor. As the beets roast, they release their juices, resulting in a dish streaked with vibrant flourishes of color. …