Mix ingredients for the yakiudon sauce (hoisin, soy sauce, sweet soy sauce, sesame oil, sambal oelek) and set aside.
Bring a large pot of water to boil and cook the frozen udon according to package instructions, usually around 2 minutes. Drain and set aside. Note: If you haven't chopped your veggies yet, you can do this while waiting for the water to boil.
In a large wok, heat a small amount of oil and add sliced pork. Stir fry until pork is cooked through, and remove it from the wok.
Add a little more oil to the wok along with garlic and ginger. After a few seconds, when the garlic and ginger have begun cooking and are very fragrant, add onions.
Stir fry onions a couple minutes, and as they start to become translucent, add the cabbage and mushrooms.
Continue to stir fry another few minutes, and when the cabbage and mushrooms have begun to soften as they cook, add the shredded carrots and return the sliced pork to the wok. Add the cooked udon noodles as well and pour the prepared yakiudon sauce over everything.
Mix everything well. Taste and adjust seasonings (e.g. add more soy sauce or hot sauce) according to tastes. Turn off the heat and serve immediately. Leftovers can be kept in an airtight container in the fridge for a couple days.