Preheat the oven to 220C, fan-forced. Line an oven tray with baking paper. Cut the unpeeled sweet potato into 1cm-thick fries. Put the fries on the lined tray, drizzle with 3 tsp olive oil, season with salt and pepper and toss to coat. Bake on the upper oven shelf for 23-25 mins until golden and tender.
Step 2 — Prep ingredients
Meanwhile, thinly slice the tomato. Cut the bread rolls in half. Put the beef mince and barbecue seasoning in a large bowl. Using damp hands, combine well, then shape into 2 equal portions.
Step 3 — Cook beef patties
Heat 2 tsp olive oil in a medium frypan over medium-high heat (see Kitchen 101). Add the beef portions and press down on each with a spatula to flatten into a patty slightly larger than the base of a bread roll. Cook for 2-3 mins each side until just cooked through. Remove the pan from the heat.
Step 4 — Bake rolls
While the patties are cooking, put the rolls on an oven tray, cut-side up, and bake on the lower shelf for 5-6 mins until lightly toasted. Combine 1 tsp olive oil and 1 tsp red wine vinegar in a large bowl and season with salt and pepper. Add the spinach and toss to coat.
Step 5 — Serve up
Spread the roll bases with the mayonnaise and spread the tops with the barbecue sauce. Layer the bases with the beef patties, tomato and some of the spinach, then sandwich with the tops. Serve with the sweet potato fries and remaining spinach. Enjoy!
Step 6 — Kitchen 101
'Smash' burgers are formed by flattening the beef portions in the pan rather than shaping them into patties before cooking. Make sure your pan is hot before adding the beef so it browns nicely. If you like, top the beef with baking paper before flattening to prevent the spatula sticking.