Step 1Steam or microwave sweet potato for 4–5 minutes, or until tender. Place the sweet potato, cannellini beans, the smoked paprika and cumin in a large bowl and mash until almost smooth. Stir through quinoa, red onion and egg.
Step 2Shape mixture into 4 large patties. Place on a tray lined with baking paper and refrigerate for 10 minutes to firm slightly.
Step 3Spray a large non-stick frying pan with olive oil and set over medium heat. Add patties. Cook, turning once, for 10–15 minutes, or until golden brown.
Step 4Spread the base of each roll with crumbled feta. Top with baby spinach, grated beetroot, a sweet potato patty, sliced tomato and roll lid, to serve.