Soak the sliced pork in cold water for 15minutes, then drain.
Put 6 cups of water into a pot to boil.
Peel and cut the carrots and potatoes and quarter the tomatoes.
Heat oil in a pan until medium hot, add tomatoes, carrots, and potatoes separately, sautéing each ingredient for 1 minute before adding the next.
Transfer the vegetables into the pot of water, and bring to a boil.
Add the pork, cover the pot and allow the soup to come back to a boil.
Stir the pork slices to loosen them, reduce to medium heat and cook for 20 minutes.
Remove the tomato skin, and add salt to taste.