Vegetable oil, for searing (or other neutral oil)
2 pounds beef short ribs
Kosher salt and black pepper
1 yellow onion, sliced
1 teaspoon dried thyme
1 teaspoon to 1 tablespoon all-purpose flour (See Note)
1 quart unsalted or low-sodium beef stock
3 dried bay leaves
Heat the oven to 350˚F.
Heat a thin layer of oil in a Dutch oven or other large oven-safe pot with a lid over medium-high heat. Meanwhile, pat the short ribs dry with paper towels and season all over with salt and pepper. Sear the short ribs (in batches if necessary) until browned all over, adding more oil as needed, and then transfer to a platter.
In the same pot, add the onion, thyme, and some salt and pepper (and more oil if the pot is dry), and cook, stirring occasionally, until the onions start to soften, a few minutes. Sprinkle with the flour and cook for about 1 minute more while stirring.
Add the beef stock, bay leaves, and browned short ribs back to the pot, let come to a simmer, cover, and place in the oven until tender, about 2 hours. Serve.