Preheat the oven to 180C, fan-forced. Halve the carrot and cucumber widthwise, then thinly slice. Stack the slices and cut into thin matchsticks. Pick the coriander leaves, discarding the stems.
Step 2 — Pickle veggies
Put 1 tbs white vinegar, 3 tsp sugar and 2 tsp boiling water in a large bowl and stir until the sugar dissolves. Add the carrot and cucumber and toss 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 — Cook beef stir-fry
Meanwhile, separate the beef stir-fry. Heat 2 tsp vegetable oil in a large frypan over high heat until very hot (see Kitchen 101). Stir-fry the beef for 1-2 mins until browned. Remove from the pan. Remove the pan from the heat.
Step 5 — Serve up
Drain the pickled veggies. Spread the rolls with 2 tbs mayonnaise and fill with the pickled veggies, beef and coriander leaves. Drizzle with the sweet chilli sauce and enjoy!
Step 6 — Kitchen 101
Ensuring the pan is really hot before adding the beef prevents it from stewing and gives it a nice browned finish.