Prep your pork tenderloin by removing the silver skin, cutting in half lengthwise, and then thinly slicing. Cut the vegetables into thin strips and set aside. Mince the garlic.
Mix together all of the sauce ingredients and set aside.
Preheat your griddle or a large wok on the stovetop over medium-high heat. Add one tablespoon of oil and cook the meat in batches. Cook until it is no longer pink and then remove to a plate.
Add another tablespoon of oil to the griddle or wok.
Cook the vegetables in batches until tender crisp.
Remove to the plate with the meat and cover.
Add the remaining tablespoon of oil to the wok. Put your fresh udon in and then add 1/2 cup of water to the wok and cover. Let the udon steam for 2-3 minutes and then flip and cover again. The steaming process will soften and loosen the noodles.
Once softened, gently break apart, add in the pork and vegetables, and toss to combine.
Reduce the heat to medium. Whisk the sauce ingredients to redistribute the cornstarch. Pour the sauce mixture over everything and start stirring immediately.
Let it cook until the sauce thickens and coats all of the ingredients.
Serve hot with a few shakes of sesame seeds if you want, for garnish.