Preheat the oven to 200C, fan-forced. Line an oven tray with baking paper. Cut the unpeeled sweet potatoes into thin wedges. Put on the lined tray, drizzle with 2 tsp olive oil, season with salt and pepper and toss to coat. Bake for 20 mins or until golden and tender.
Step 2 — Prep and cook onion
Meanwhile, thinly slice the onion into rings. Heat 2 tsp olive oil in a medium frypan over medium-high heat. Cook the onion, stirring regularly, for 4 mins or until golden and softened. Remove from the pan, reserving the pan.
Step 3 — Make beef patties
While the onion is cooking, put the beef mince, breadcrumbs and barbecue seasoning in a large bowl. Using damp hands, combine well, then shape into 2 equal patties, slightly larger than the base of a bun.
Step 4 — Cook patties
Heat 2 tsp olive oil in the reserved pan over medium-high heat. Cook the beef patties for 3 mins each side or until cooked through. Transfer to a plate and drizzle over any pan juices.
Step 5 — Make salad
Thinly slice the tomato. Shred the carrot using a julienne peeler or coarsely grate with a box grater. Whisk 1 tsp red wine vinegar and 1 tsp extra virgin olive oil in a large bowl and season with salt and pepper. Add the carrot and salad leaves and toss to combine.
Step 6 — Toast buns and serve
Halve the buns through the middle. Put on an oven tray, cut-side up, and bake for 4-6 mins until lightly toasted. Spread the buns with the burger sauce. Divide the patties, tomato, onion and some of the salad among the bun bases, then sandwich with the bun tops. Serve the burgers with the sweet potato wedges and remaining salad.