To make the sauce, combine the ingredients in a small bowl and set aside.
Heat a large, heavy-based skillet over medium-high heat. Add the onion and garlic and cook, stirring for 1-2 minutes until fragrant.
Add the beef mince and cook, stirring for 3-4 minutes until browned, breaking it up with your spoon as you go.
Add the sauce and cook for 1-2 minutes until caramelised.
Add the broccoli, place the lid on and cook for 1-2 minutes.
Push the beef and broccoli mixture to the outside of the pan to make a well in the middle.
Pour in 1.5 cups of water and add the uncooked noodles to the centre of the pan. Cook, covered, without stirring for 1 minute. Flip the noodles and cook for another 1 minute, covered, or until the noodles are just pliable.
Using tongs, toss the noodles through the beef and broccoli.
Combine the corn flour with the remaining ¼ cup of water.
Add the corn flour and water mixture to the stir-fry and cook, tossing with tongs for 1-2 minutes or until the sauce has thickened and created a lovely glaze around the noodles.
Season to taste with the tamari or soy sauce.
Serve scattered with sesame seeds and sliced spring onions.
