Preheat the oven to 325 degrees. Season the beef generously with salt and pepper. In a large ovenproof pot with a lid, heat 2 tbsp. oil over high. Working in batches, cook the beef until browned all over, 5 to 10 minutes per batch, adding remaining oil by the tablespoon between batches.
Return the beef to the pot. Add 8 cups stock and the next 7 ingredients and bring to a boil. Cover the pot and transfer to the oven. Cook until the beef is tender, 2 to 2 1/2 hours.
Add the carrots; cover partially and cook just until tender, about 20 minutes. Transfer the pot to the stovetop. In a bowl, whisk the remaining 1 cup stock and the flour until smooth. Add the flour mixture to the pot. Bring to a boil, stirring often; cook until thickened, about 2 minutes. Let the stew cool, uncovered, 3 hours.
Freeze in 2-cup portions.