Tender braised beef short ribs meet a deconstructed haroset, the hallowed condiment made from apples and wine. This braise is best if made ahead, but you can also prepare and serve it for Passover dinner the same day.
Preheat oven to 325 degrees. Place racks in middle and lower thirds. Pat dry short ribs with paper towels and generously season with salt and pepper. Heat 1 tablespoon oil in a large Dutch oven over medium-high heat. Working in 2 batches, and adding more oil if necessary, sear short ribs on all sides until deep golden brown, about 4 minutes per side, transferring to a clean plate as seared. Wipe out pot.
Heat 2 tablespoons oil in pot over medium heat. Add chopped carrots, celery, and onion, season with salt and pepper, and cook, stirring occasionally, until softened, about 8 minutes. Add cinnamon and stir until vegetables are evenly coated. Add wine, vinegar, and herbs, scraping up the browned bits with a wooden spoon. Add short ribs and any accumulated juices to pot, nestling them into vegetables and liquid to form a single layer. Bring to a simmer, cover pot, and transfer to oven. Braise until short ribs are very tender, 3 to 3 1/2 hours.
Meanwhile, toss walnuts with remaining tablespoon oil on a rimmed baking sheet and season with salt and pepper. Toast on lower oven rack until golden brown, 20 to 25 minutes, tossing halfway through. Let cool.
Remove short ribs from pot; season with salt. Pour braising liquid through a fine sieve into a bowl, pressing on solids to remove as much liquid as possible. Discard solids and transfer liquid to a fat separator; pour off fat.
If serving short ribs the same day, return liquid to pot and proceed to step 6. Otherwise, they can be refrigerated up to 5 days. Before proceeding to step 6, reheat ribs, then transfer them to a bowl; keep lightly covered with plastic wrap to prevent them from drying out.
Add reserved halved carrots to pot and simmer until crisp-tender, about 13 minutes. Add apples and simmer, stirring occasionally, until both carrots and apples are tender, about 12 minutes more. Braising liquid should be thick enough to coat the back of a spoon; if it's not, transfer carrots and apples to bowl with short ribs and reduce braising liquid until thickened. Season sauce with salt and pepper. Discard bay leaf. Divide short ribs, carrots, and apples among 8 shallow bowls, spooning braising liquid around. Garnish with walnuts and parsley sprigs.