Start by preparing all your ingredients, mince the garlic, dice the carrots and onions and puree or grate the tomatoes.
Pat dry the oxtail pieces well with paper towels to help the exterior achieve a better browning when searing.
On a large skillet or heavy cooking pot, heat the cooking oil then place the oxtail pieces to brown them on all sides then set them aside. You can do this in batches to avoid overcrowding the pan.
On the same pan, add in the butter and once it has melted, add the diced onions and allow to cook till slightly translucent.
Stir in the diced carrots and allow to cook for about 3 minutes for flavor to start developing.
Next add in the minced garlic and let it cook for about a minute.
Stir in the tomato paste together with all the spices, sea salt and black pepper. Allow to cook for another minute.
Add the red wine vinegar and deglaze the cooking pot. Let it cook for two minutes then stir in the tomatoes. Cover the pot and allow them to cook on medium to low heat for about 5 minutes.
Uncover the pot and add in the herbs, bay leaves and sugar then stir everything together.
Add back the oxtail and mix them well with the tomato sauce then add the beef stock or vegetable stock or water. Stir, cover and allow to cook slow cook on low heat for up to 3-4 hours on the stove top or in a pre heated oven at 160°C for 3-4 hours till the meat falls of the bone or it's very tender. You can check the meat every 1 hour to replenish the stock or water if necessary. Once ready, garnish with some cilantro leaves then serve with your favorite sides and enjoy.