Preheat the oven to 180°C.
Heat half of the oil in a casserole dish in the oven until smoking.
Toss raw potato cubes in the hot oil until evenly coated.
Stir in spices, garlic, and chilli to coat the potatoes and season with salt and pepper.
Roast for 20 to 25 minutes until crisp, then drain on kitchen paper and cool slightly.
Mix the roasted potatoes into the mashed potatoes.
Shape the mixture into 20 to 24 small patties measuring 5cm.
Dredge each patty in seasoned flour.
Fry patties in batches in the remaining oil for 2 to 3 minutes per side until golden.
Blend coriander, mint, salt, and vinegar in a food processor, then stir in the yoghurt.
Serve the hot potato cakes with the prepared sauce.