Use a sharp cleaver to cut through oxtail cartilege and divide into small sections.
Bring 8 cups water to a boil in a medium saucepan.
Add oxtail sections, 1 cup tomatoes and wine.
Cover and simmer 3 hours over low heat until meat is tender.
Heat a small skillet over medium heat 30 seconds to 1 minute.
Add flour and stir-fry until golden brown.
Remove from skillet; set aside.
Heat 1/4 cup oil in skillet over medium heat 1 minute.
Add onion; stir-fry 1 minute.
Add carrot and remaining tomatoes.
Stir-fry 2 minutes.
Add 1 cup oxtail.
Simmer over low heat until carrot slices are tender.
Heat 2 tablespoons oil in a wok over medium heat 30 seconds.
Add cooked flour; stir-fry 2 seconds.
Add 2 cups oxtail broth to cooked flour; mix thoroughly to make a paste.
Stir in ketchup, soy sauce and salt.
Add stewed vegetables.
Cook over low heat 3 minutes.
Add cooked oxtail; stir to mix.
Bring to a boil.