Start by thinly slicing the beef and placing in a bowl. Dust with cornflour, ensuring each piece is lightly coated and set aside. Prepare the stir-fry sauce by combining all ingredients in one bowl, set aside. Bring a large pan of water to the boil and add the udon noodles. Allow them to soften in the water for 2 minutes, then use tongs to gently loosen them. As soon as the noodles come apart, drain and rinse under running water to cool them and stop them from cooking further. Set aside for later.

Grab your MAKO wok, heat the vegetable oil over high heat. Add the beef slices and stir-fry for 2-3 minutes until they are browned and just cooked through. Remove the beef from the pan and set aside. In the same pan, add a little more oil if necessary, then stir-fry the onion, capsicum, spring onions, garlic, and ginger for 2-3 minutes or until the vegetables are tender but still crisp.

Return the beef to the pan and pour in the prepared stir-fry sauce. Stir everything together, ensuring the beef and vegetables are evenly coated in the sauce. Add the cooked noodles to the pan and toss to combine, allowing the noodles to absorb the sauce. Serve the Mongolian Beef Noodles immediately, garnished with extra spring onions or sesame seeds if desired.