Prepare udon according to packet instructions.
Add 1tablespoon of oil in a large frying pan or wok on high heat. Add shiitake mushrooms and cook until lightly golden, about 1 minute.
Add onions, white parts of green onions, garlic and carrots. Stir fry for 1 minute then add cabbage, cook on medium-high heat for 3 to 4 minute or until vegetables soften.
Push vegetables to the rims of the pan, clearing space in the middle of the pan. Add remaining 1 tablespoon of oil then pork belly. Stir fry the pork belly (without mixing vegetables in) on high heat for about 1 minute then add seasoning. Mix everything through.
Add udon and toss through with 2 spatulas (or chopsticks), one in each hand to help with even distribution of seasoning and vegetables. About 2 to 3 minutes.
Serve immediately with bonito flakes and Japanese pickled ginger.