Preheat the oven to 220C, fan-forced. Line an oven tray with baking paper. Cut the potatoes into 1.5cm-thick fries. Put the fries on the lined tray, drizzle with 2 tsp oil, scatter over the Chinese barbecue seasoning, season with salt and pepper and toss to coat. Roast for 23-25 mins until golden and tender.
Step 2 — Prep vegetables
Meanwhile, peel the cucumber into ribbons using a vegetable peeler. Shred the carrot using a julienne peeler or cut into thin matchsticks. Thinly slice the cabbage with a sharp knife or mandoline. Thinly slice the spring onion.
Step 3 — Make patties
Put the pork mince and half the char siu sauce in a large bowl and season with salt and pepper. Using damp hands, combine well, then shape into 2 equal patties, slightly larger than the base of a bread roll.
Step 4 — Cook patties
Heat 2 tsp oil in a medium frypan over medium-high heat. Cook the patties for 3 mins each side or until cooked through. Add the remaining char siu sauce and 1 tbs water to the pan and gently turn the patties until the sauce is sticky and the patties are coated.
Step 5 — Heat bread rolls
While the patties are cooking, halve the bread rolls through the middle. Put on an oven tray, cut-side up, and bake for 3-4 mins until heated through.
Step 6 — Toss salad and serve
Combine 2 tsp white vinegar and 1 tsp soy sauce in a large bowl. Add the cucumber, carrot and cabbage and toss to combine. Fill the bread rolls with the patties and any pan juices and some of the salad. Divide the pork burgers, oven fries and remaining salad among plates. Scatter the spring onion over the fries to serve.