Season the oxtails liberally with salt and pepper. Heat the olive oil over medium heat in a heavy bottomed pan. Brown the oxtails and set aside.
To the pan, add the beef broth, garlic cloves, basil, oregano, bay leaves, and diced tomatoes with their juice. Return the oxtails along with any accumulated juices to the pan. Bring to a boil, then reduce the heat to maintain a steady simmer. Cover and cook for 2 1/2 hours.
Add the onion, potatoes, and carrots to the pan and continue cooking for an additional 30-40 minutes or until the vegetables are tender.
Use a slotted spoon to remove the vegetables and oxtails from the pan. In a small bowl, combine the butter and flour to create a smooth mixture. Increase the heat to medium and whisk the butter-flour mixture into the broth a spoonful at a time. Taste for seasoning and add salt if needed.
Return the oxtails to the thickened broth turning them to coat.
Serve the vegetables and oxtails with sauce over hot, steamed rice.
While it's not absolutely necessary to brown the oxtails before stewing them, it is highly recommended. Browning meat results in caramelization which greatly enhances the flavor of the finished stew. It also produces a beautiful color in the finished recipe. StorageStore the stew and rice in separate containers in the refrigerator for up to 4 days.ReheatingTo reheat the stew, place it in a saucepan on the stove over medium-high heat until it comes up to temperature. For the rice, place it in a pot, add a few tablespoons of water, break up any clumps you see and seal with a tight lid. Heat on medium-low, and make sure you check often to avoid the rice sticking to the pan.