Preheat the oven to 220C, fan-forced. Line 2 oven trays with baking paper. Cut the unpeeled sweet potatoes into 1.5cm-thick chips. Thinly slice the onion.
Step 2 — Bake vegetables
Put the sweet potato and onion separately on the lined trays. Drizzle with 2 tsp olive oil, season with salt and pepper and toss to coat. Spread into a single layer. Bake the sweet potato on the upper oven shelf for 10 mins. Put the onion on the lower shelf. Bake the vegetables for a further 12-15 mins until browned and tender.
Step 3 — Cook pork patties
Meanwhile, put the pork mince and barbecue seasoning 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. Heat 2 tsp olive oil in a medium frypan over medium-high heat. Cook the patties for 3 mins each side or until cooked through.
Step 4 — Bake bread rolls
Halve the bread rolls through the middle. Put the bread rolls, cut-side up, on a separate oven tray. (If you don't have three oven trays, move the onion to one side of the tray to make room for the bread rolls.) Bake for 3-4 mins until lightly toasted.
Step 5 — Dress zucchini
While the bread rolls are baking, put 1 tsp extra virgin olive oil, ½ tsp red wine vinegar and ¼ tsp dijon mustard in a large bowl, season with salt and pepper and whisk to combine. Peel the zucchini into ribbons with a vegetable peeler. Add the zucchini to the dressing and toss to coat.
Step 6 — Get ready to serve
Spread the bread rolls with the aioli. Divide half the dressed zucchini among the roll bases, top with the pork patties and onion and sandwich with the roll tops. Serve the burgers with the sweet potato chips and remaining dressed zucchini.