Cut the green onions into 2 inch pieces. Cut the white part of the green onions in half lengthwise.
Cut the carrot into thin slabs then cut them in half.
Cut off the core of the cabbage leaves and chop them into small squares.
Remove the stem of the shiitake mushrooms and slice them thinly.
Cut the thinly sliced pork belly into small pieces.
Boil the udon noodles according to the package instructions. These frozen sanuki udon are precooked and needed to cook for 1 minute in the boiling water. Drain well.
In a large frying pan, heat the oil over medium heat and start cooking the white parts of the green onion.
Add the pork belly and season with salt and black pepper.
When the pork is no longer pink, add the carrot and cook for a few minutes. Then add the rest of the tender vegetables.
Stir to cook until everything is cooked through.
Add the udon noodles and toss to combine with the ingredients.
Add sugar and sake.
Add the soy sauce and sesame oil. Toss to coat with the seasonings.
Serve hot and sprinkle katsuobushi (bonito flakes).