Julienne the onion, carrot, green onion, and cabbage.
Cut the pork into bite-sized pieces.
Heat cooking oil in a pan and stir-fry the pork.
When the pork is about halfway cooked, add the prepared vegetables and continue stir-frying.
Blanch the udon noodles in boiling water, then add them to the pan.
Add the sauce (soy sauce, mirin, sugar, pepper) and stir-fry together with all the ingredients.
Once everything is well combined, transfer to a plate and serve.