Marinate 300g of thinly sliced stir fry beef with 1 tbsp light soy sauce, 1 tbsp mirin, 1 tbsp sesame oil, 1 tbsp honey, some white pepper, 3 cloves of minced garlic and some white sesame oil. Mix well and refrigerate for 30 minutes.
Boil a pot of water. When the water boils, add 1 cup of penne. Let it cook for 9 minutes or as per the cooking time stated in the box. There will be a bit more cooking in a pot later. So, you can cook a minute lesser if you want it to be more al dente. Once cooked, strain and set aside.
Chop 3 to 4 stalks of spring onion. Chop finely for the white part and cut into lengths of about 5cm for the green part.