Bring a large pan of slightly salted water to the boil then add the spaghetti. Cook according to the instructions on the packet (usually about 15-20 minutes in boiling water). You can check to see if the spaghetti is cooked by removing a strand on the end of a fork.
Meanwhile slice the pork into small pieces and mix it in a small bowl with the Soy sauce. Chop the tomatoes into small pieces, discarding the seeds from inside and retaining just the firm flesh. Peel and chop the carrots and chop the cabbage into small pieces.
Place the corn oil in a large frying pan (or wok) and heat until you detect a haze. Drop in the pork and stir until it is browned (about 1 or 2 minutes). Add the carrot and cabbage and continue to fry until they are tender (about 5-6 minutes). Drain the spaghetti in a colander or large sieve (strainer) and add to the frying pan (I told you you'd need a large one!). Add the tomatoes, tomato ketchup, chili sauce, oyster sauce and sugar. Heat the whole mix for a further 4-5 minutes, stirring all the time, then serve immediately.