Preheat oven to 180C/Gas 5. Top, tail, de-seed and quarter the red pepper. Brush with olive oil, place on a roasting tin and roast for 20 mins. When tender, remove from oven, chop finely and set aside.
Peel sweet potato and potato, cut into chunks, place in a saucepan, cover with water, bring to a boil over a medium heat and simmer until just tender. Drain thoroughly and mash.
Add red pepper, chilli and coriander to mashed potato and season well. Stir in half the breadcrumbs, carrot and seeds to make a soft dough. Mix well and shape into 4 burgers.
Lightly whiz remaining breadcrumbs in a food processor to make finer crumbs, pour onto a plate and use to coat the burgers.
Heat the oil in a frying pan and fry the burgers for 3-4 mins on each side until golden. Serve in burger buns with salad leaves and grated radish.
Recipe by appetite magazine at https://www.appetitemag.co.uk/sweet-potato-burger/