For the ‘cakes’, place the sweet potatoes in a small pan and pour over enough boiling water to cover. Top with a lid and cook on a medium heat until soft to the point of a knife. Drain and put in a bowl to cool.
Mix the potatoes with the self-raising flour and baking powder, then stir in the horseradish sauce.
Divide the mixture into 4 patties. Put 1 tbsp of the flour onto a small plate and dip each patty in to coat.
Heat the oil in a frying pan and cook the patties for about 1-2 minutes on each side until golden brown. Remove from the pan and place on a plate.
For the topping, heat the oil in a frying pan and cook the slices of courgette on a medium heat until golden brown.
Place a slice of tomato on top of each potato cake, then wrap each one with a ribbon of courgette.
Place 1/4 of the crab meat on top of each tomato. Serve sprinkled with chives and a salad (optional).