This easy beef yaki udon stir-fry is made with tender beef sirloin, thick and chewy udon noodles, crisp vegetables, and a savory homemade sauce. It is a quick, family-friendly meal that comes together easily and is perfect for busy weeknights.
1 In a small bowl, whisk together the dark soy sauce, oyster sauce, mirin, brown sugar, rice wine vinegar, and minced garlic. Set aside.
2 Prepare the udon noodles according to the package instructions. Drain well and gently separate the noodles.
3 Heat the avocado oil in a large skillet or wok over medium-high heat.
4 Add the thinly sliced beef sirloin and cook for 2 to 4 minutes, or until browned and mostly cooked through. Transfer the beef to a plate and set aside.
5 Add the onion and red bell pepper to the same skillet. Cook for 2 to 3 minutes, stirring frequently.
6 Add the bok choy and cook for another 1 to 2 minutes, or until slightly softened but still crisp.
7 Add the udon noodles and prepared sauce to the skillet. Toss everything together until the noodles and vegetables are evenly coated.
8 Return the beef to the skillet and add the scallions.
9 Cook for another 1 to 2 minutes, tossing frequently, until the beef is fully cooked and everything is heated through.
10 Serve immediately.
