Preheat the oven to 180C, fan-forced. Shred the carrot using a julienne peeler or cut into thin matchsticks. Thinly slice the cucumber lengthwise, stack the slices, then cut into thin strips.
Step 2 — Pickle vegetables
Put 2 tsp rice wine vinegar and 2 tsp sugar in a large bowl, season with salt and stir until the sugar dissolves. Add the carrot and cucumber and toss well to combine. Set aside to pickle, tossing occasionally, until needed.
Step 3 — Warm rolls
Cut a slit lengthwise down the middle of the rolls, taking care not to cut all the way through. Put the rolls on an oven tray and bake for 8 mins or until warmed through and crusty.
Step 4 — Start chicken
While the rolls are baking, thinly slice the chicken into strips. Heat 2 tsp oil in a medium frypan over medium-high heat. Stir-fry the chicken for 2-3 mins until golden and cooked through. Remove from the pan and reserve the pan.
Step 5 — Finish chicken
Combine the pho seasoning, 1 tsp rice wine vinegar, 2 tsp water, 1 tsp sugar and 1 tsp soy sauce in a bowl and season with pepper. Return the chicken to the reserved pan over medium-high heat. Add the pho seasoning mixture and cook, tossing, for 1 min or until coated.
Step 6 — Make nuoc cham and serve
Combine the sweet chilli sauce, ½ tsp rice wine vinegar* and ½ tsp soy sauce in a bowl, then season with pepper. Pick the coriander leaves, discarding the stems. Divide the rolls among plates, fill with half the pickled vegetables and the chicken. Drizzle with the nuoc cham, scatter with the coriander and serve with the remaining pickled vegetables.