Bring a medium saucepan of water to the boil for the noodles. Slice the capsicum. Trim the beans and halve on an angle. Pick the coriander leaves and finely chop the stems. Combine the fish sauce, sesame oil, half the red galangal seasoning, 2 tsp sugar, 2 tsp soy sauce, 1 tsp white vinegar and 2 tbs water in a bowl.
Step 2 — Make omelette
Whisk 2 eggs and ½ tsp water in a bowl. Heat 2 tsp oil in a medium deep frypan over medium-high heat. Add the egg mixture and swirl to coat the base of the pan. Cook for 1 min or until just set, then loosely roll up the omelette in the pan. Transfer to a board and cool slightly, then cut into strips.
Step 3 — Stir-fry prawns
DOUBLE THE PRAWNS OPTION Heat 1 tbs oil in the same pan over medium-high heat. Stir-fry the prawns for 2 mins or until almost cooked through. Add the coriander stems and remaining red galangal seasoning and stir-fry for 30 secs-1 min until the prawns are just cooked through. Remove from the pan.
Step 4 — Stir-fry vegetables
Heat 2 tsp oil in the same pan over high heat. Stir-fry the beans and capsicum for 2-3 mins until just tender.
Step 5 — Cook noodles
While the vegetables are cooking, 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
Meanwhile, thinly slice the spring onion. Add the noodles, sauce mixture and prawns to the vegetables and season with pepper. Cook, tossing, for 1 min or until heated through and combined. Divide the noodles and omelette strips among bowls. Scatter with the spring onion and coriander leaves to serve.