Yaki Udon (Japanese Stir-fried Udon Noodles)

If using fresh, dried, or pre-cooked udon noodles: Boil the udon noodles according to the package instructions. Once cooked, drain them in a colander.
If using frozen udon noodles: Lightly sprinkle water over the udon noodles. Then, place them on a microwave-safe plate, cover with plastic wrap, and microwave on medium power (500W) for about 4 minutes. You can also cook them by boiling, just like the other types of udon noodles.
Cut carrot and onion into long, bite-sized strips. Tear cabbage into bite-sized pieces. Cut pork belly into pieces about ⅗ inch (1.5cm) wide.
Mix seasonings (sake, mirin, and soy sauce) in a bowl.
Heat oil in a pan. Once the pan is hot, add the pork, sprinkle it with salt and black pepper, and sauté until it changes color. Then, add the vegetables in order of firmness (carrot, onion, and cabbage), and stir-fry until they are tender.
Move the stir-fried ingredients to one side of the pan and add the udon noodles to the empty space. Pour the seasoning mixture from the bowl over the udon noodles and mix well. Once the udon noodles are evenly coated with the seasoning, combine them with the other ingredients. Then, cover the pan with a lid and steam over low heat for 2 minutes.
Remove the lid and cook until most of the remaining moisture has evaporated.
Serve on a plate and sprinkle bonito flakes on top.