Step 1

Combine the sweet potato, flour, egg, cumin and garlic in a bowl. Place the aïoli, lime rind and lime juice in a small bowl. Season with pepper and stir to combine.

Step 2

Heat half the oil in a non-stick frying pan over medium heat. Shape the sweet potato mixture into 8 patties. Add half the patties to the pan and cook, pressing down to flatten, for 2-3 minutes each side or until golden. Transfer to a tray lined with paper towel. Repeat with the remaining oil and patties.

Step 3

Meanwhile, preheat grill on high. Place the bread rolls, cut-side up, on a baking tray and cook under grill for 1 minute or until light golden.

Step 4

Divide the rocket and rosti among the bread bases. Top with the aïoli, onion and bread tops.