Crush or finely chop the garlic. Crumble the stock cubes into a medium saucepan, then add the Asian-style stock powder, garlic and 1L (4 cups) boiling water. Cover and bring to the boil over high heat. Bring a separate medium saucepan of water to the boil for the noodles (speed things up by using a kettle to boil the water).
Step 2 — Prep vegetables
Meanwhile, halve the carrot lengthwise, then thinly slice on an angle. Coarsely chop the pak choy stems and keep the leaves whole. Slice the spring onion.
Step 3 — Cook carrot
Add the carrot, 2 tsp soy sauce, 1 tsp white vinegar and ½ tsp sugar to the boiling stock, then reduce the heat to medium. Cook for 5 mins or until the carrot is just tender.
Step 4 — Stir-fry beef
While the carrot is cooking, separate the beef stir-fry. Heat a drizzle of oil in a large frypan over high heat until very hot (fast and hot cooking is key to a great stir-fry). Stir-fry the beef for 1-2 mins until browned. Transfer the beef to a bowl, add 2 tsp soy sauce, season with pepper and toss to coat.
Step 5 — Cook noodles
Cook the noodles in the pan of boiling water for 2 mins or until tender. Drain, then rinse under hot water to prevent the noodles from sticking.
Step 6 — Get ready to serve
Add the pak choy stems to the stock and cook for 1 min or until tender. Add the pak choy leaves and sesame oil and remove the pan from the heat. Divide the noodles and beef among bowls, then ladle over the soup and vegetables. Scatter over the spring onion and sesame seeds to serve.