Thinly slice the spring onion on an angle. Crush or finely grate the garlic. Separate the pork stir-fry. Combine the pork, prawns, half the spring onion, half the garlic, half the pho seasoning, ¼ tsp turmeric and 1 tsp sugar in a bowl. Season with salt and pepper. Preheat the grill to high.
Step 2 — Prep salad
Cut the cucumber into thin batons. Shred the carrots using a julienne peeler or coarsely grate with a box grater. Pick the mint leaves, discarding the stems. Juice the lime. Combine the lime juice, fish sauce, remaining garlic, a pinch of chilli flakes* (omit if preferred) and 3 tsp sugar in a large bowl. Add the cucumber, carrot and mint and toss to combine.
Step 3 — Grill pork and prawns
Bring a medium saucepan of water to the boil for the noodles. Halve the rolls through the middle, taking care not to cut all the way through. Line an oven tray with foil. Put the rolls on the lined tray and grill for 4-5 mins until lightly toasted. Set aside. Put the pork and prawns on the tray, keeping them separate, and grill for 8 mins or until cooked through.
Step 4 — Cook noodles
Meanwhile, cook the noodles and ½ tsp turmeric* in the pan of boiling water for 7-8 mins until the noodles are tender. Drain, then rinse under cold water to prevent the noodles from sticking.
Step 5 — Make soup
While the noodles are cooking, combine the remaining pho seasoning, 500ml (2 cups) water, 1 tsp sugar and 1 tsp soy sauce in a small saucepan and bring to the boil. Remove from the heat and cover to keep warm.
Step 6 — Get ready to serve
Reserve half the salad, leaving the remaining salad in the bowl. Add the prawns and noodles to the bowl and toss to combine. Scatter with peanuts. Fill rolls with aioli, reserved salad, pork and shallots, then halve using a serrated knife. Divide soup among bowls. Scatter with remaining spring onion. Serve the rolls and soup with the salad.