Preheat the oven to 200C, fan-forced. Line a large oven tray with baking paper. Peel the sweet potatoes and cut into 3cm chunks. Put in a microwave-safe bowl, add 1 tbs water, cover and microwave for 8 mins or until tender (see Kitchen hack). Drain, then return to the bowl. Add half the barbecue seasoning*, then coarsely mash. Lightly season with salt and pepper.
Step 2 — Pickle onion
Meanwhile, very thinly slice the onion. Combine 2 tsp white wine vinegar and 1 tsp sugar in a bowl and season with salt and pepper. Add the onion and toss to coat. Set aside to pickle, tossing occasionally, until needed.
Step 3 — Bake tacos
Put the tortillas on the lined tray. Divide the sweet potato mixture among the tortillas and spread evenly, leaving a 1cm border. Scatter with the cheese. Bake for 8 mins or until warmed through and the cheese is melted.
Step 4 — Dress salad leaves
While the tacos are baking, combine 2 tsp olive oil and 1 tsp white wine vinegar in a large bowl and season with salt and pepper. Add the salad leaves and toss to coat.
Step 5 — Serve up
Divide the tacos among plates. Top with the drained pickled onion and some of the salad leaves. Spoon over the burger sauce, then fold in half to enclose the filling. Serve with the remaining salad leaves and enjoy!
Step 6 — Kitchen hack
Don't have a microwave? Put the sweet potato in a saucepan of cold salted water and bring to the boil. Reduce the heat to medium and cook for 12-14 mins until tender. Drain, then continue with the recipe.