Instructions

1. Prepare the following, placing them all in the same large bowl: Dice 1 large yellow onion (about 1 1/2 cups), dice 3 celery stalks (about 1 1/2 cups), and 1 large fennel bulb (about 1 1/2 cups). Thinly slice 3 garlic cloves. Add 1 teaspoon fennel seeds.
2. Place 3 pounds beef short ribs on a baking sheet and season with 1 tablespoon of the kosher salt. Heat 2 tablespoons olive oil in a large Dutch oven or heavy-bottomed pot over medium-high heat until shimmering. Working in batches, sear the short ribs until browned all over, 2 to 3 minutes per side. Return the short ribs to the baking sheet. Meanwhile, core and thinly slice 1/2 medium head red cabbage until you have about 3 cups. Peel and chop 1 pound beets.
3. Reduce the heat to medium. Remove and discard all but 2 tablespoons fat from the pot. Add the onion mixture to the pot. Cook, scraping up any browned bits from the bottom of the pot, until the vegetables are soft and translucent, about 12 minutes.
4. Add the cabbage and cook, stirring occasionally, until wilted, about 5 minutes. Add the beets, 1/4 cup tomato paste, 1/4 cup red wine vinegar, remaining 1/2 teaspoon kosher salt, and 1/4 teaspoon black pepper. Stir until the vegetables are coated in tomato paste.
5. Return the short ribs and any accumulated juices to the pot. Add 6 cups beef stock and 2 bay leaves and bring to a boil. Reduce the heat to maintain a bare simmer. Cover and cook, stirring every 30 minutes and making sure to scrape the bottom of the pot, until the meat is fork tender, 2 /12 to 3 hours.
6. Using tongs, transfer the short ribs to a plate. Taste and season the borscht with kosher salt as needed. If desired, skim the fat off the surface with a spoon. When cool enough to handle, shred or cut the meat into large chunks, discarding any bones, large chunks of fat, or gristle. Return the meat to the pot and stir to combine. Serve with yogurt or sour cream, fresh dill, and freshly grated horseradish.