Begin by boiling a pot of lightly salted water on one burner, and on another put down a wok or high walled skillet and turn the heat on max.
Add the oil to the pan and once it is hot add the bell pepper and carrot. They need the longest time so we will start with them. Once the carrot and bell pepper start to soften and cook on the edges, you can add the pork. At this point you can add the noodles to the boiling water. They should only need 2-3 minutes to cook if they are fresh, otherwise follow the instructions on the package.
When the pork begins to brown, add the cabbage, soy sauce, rice wine vinegar, and garlic if you are using it. Agitate the pan/wok by shaking it, tossing if you are able. Pull the udon noodles out of the boiling water and give them a good shake. Add them to the pan or wok. Continue tossing until the noodles have fried a bit, and are browning from the heat and the soy sauce. You can add more soy sauce if you want.
Take off the heat and add some sesame seeds. Toss and serve.