Choose a pot that leaves room for the meat, tomatoes and rice as well as the liquid. Combine equal volumes of Bò broth and water, add the beef and bring to a gentle simmer. Cook until the meat is tender; depending on the cut, this can take several hours.
Soften the onions in a little marrow fat in a separate pan. Add the chopped tomatoes and cook until they break down. Stir in the garlic near the end, then add the mixture to the beef and broth.
Once the beef is tender, add the rice. Keep the soup at a gentle simmer for about 15–20 minutes, until the rice is cooked. Add more hot water if needed.
Stir in one generous teaspoon of Bò seasoning for the entire pot. Taste before adding salt. Add chopped coriander and the other herbs towards the end, then let the soup stand briefly before serving.
