Crumble 1 stock cube* into a heatproof jug, add 750ml (3 cups) boiling water and stir to dissolve. Bring a medium saucepan of water to the boil for the noodles.
Step 2 — Start laksa soup
Combine the curry paste, stock and 2 tsp sugar in a large saucepan and bring to the boil. Stir in the coconut milk, reduce the heat to low and cook, covered, for 10 mins to develop the flavour. (It's important the soup doesn't boil or the coconut milk may separate).
Step 3 — Cook noodles
Meanwhile, cook the noodles in the pan of boiling water for 7 mins or until tender. Drain, then rinse under hot water to prevent the noodles from sticking.
Step 4 — Prep herbs and chilli
While the laksa soup and noodles are cooking, pick the coriander and Vietnamese mint leaves, discarding the stems. Thinly slice the chilli, discarding the seeds if less heat is desired.
Step 5 — Cook vegetables
Add the stir-fry vegetables to the laksa soup and increase the heat to medium. Cook, covered, for 3 mins or until the vegetables are almost tender.
Step 6 — Finish laksa and serve
Stir the prawns and fish sauce into the laksa soup and cook for 2-3 mins until the vegetables are tender and the prawns are just cooked through. Remove from the heat. Divide the noodles among bowls and ladle over the laksa soup. Scatter with the fried shallots, herbs and chilli, if desired, to serve.