Instructions
Step 1
Season the oxtail to taste with salt and black pepper. In a large pot over medium-high heat, heat the oil until it’s hot and shimmering. Working in batches, add the oxtail and cook, turning occasionally, until browned, 8–10 minutes. Using tongs, transfer the oxtail to a plate and set aside.
Step 2
Add the garlic and onion to the pot, and cook, stirring occasionally, until golden, 6–8 minutes. Add the wine and continue cooking, stirring and scraping the browned bits from the bottom of the pot, until reduced by a third, 3–5 minutes.
Step 3
Return the oxtail to the pot, add the stock and tomato sauce, and season to taste with salt and pepper. Bring to a boil, then turn the heat to medium-low, cover the pot, and simmer until the oxtail is tender, 2½–3 hours.
Step 4
Uncover the pot and return to a simmer. Add the carrots and cook until tender, 15–20 minutes.
Step 5
To a small bowl, add the butter and flour. Using your fingers or a fork, knead or mash the mixture until the flour is fully incorporated and a smooth paste forms. Stir the paste into the stew and cook until slightly thick, 8–10 minutes.