Preheat the oven to 200°C/180°C fan-forced. To prepare the ingredients, peel the sweet potato and cut into 2 cm pieces. Grate the haloumi and zucchini and squeeze out any extra moisture. Finely chop the parsley and thinly slice the green apple.

Place the sweet potato in a large saucepan and cover with water. Bring to the boil and cook for 10-15 minutes or until tender. Drain and run under cold water to cool. Drain really well and return to a saucepan. Mash the sweet potato using a fork or potato masher. Measure out 1/4 cup of sweet potato mash for every patty that you will need (1 pattie per person) and place it in a medium bowl. Stir through the zucchini, haloumi, sunflower seeds, parsley and flour. Season generously with salt and pepper and shape into patties. Tip: Cooked mashed potato will keep in the fridge for up to 3 days or in the freezer for up to 1 month.

Heat a medium frying pan over a medium-high heat. Add a drizzle of olive oil and cook the patties for 3-4 minutes on each side or until golden.

Meanwhile, pop the par-baked sourdough buns in the oven to heat up. They will need about 5 minutes. Remove the buns from the oven and cut them in half.

To assemble the burger, top the base of the burger buns with the sweet potato pattie, a small handful of mixed salad leaves, green apple slices and mayonnaise. Serve any remaining mixed salad leaves on the side.