Bring a pot of water to a boil and cook the frozen udon noodles for 1 minute until they separate; drain and rinse with cold water to stop cooking.

In a small bowl, whisk together the soy sauce, oyster sauce, mirin, chili garlic sauce, sugar, and sesame oil until well combined.

Heat the vegetable oil in a large wok or skillet over high heat; add the sliced beef and stir-fry for 2-3 minutes until browned, then remove the beef from the pan and set aside.

In the same pan, add the sliced onion and carrots, cooking for 2 minutes until slightly softened.

Add the chopped cabbage and minced garlic to the pan, stir-frying for another 2 minutes until the cabbage is tender-crisp and the garlic is fragrant.

Add the cooked noodles and beef back into the pan, then pour the sauce mixture over everything.

Toss the ingredients together vigorously on high heat for 1-2 minutes until the noodles are evenly coated in the thick, glossy sauce.

Remove from heat and serve immediately, garnished with the fresh sliced green onions.