Spread the potato wedges flat on a baking tray lined with baking paper. Roast in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 20 minutes. Turn over in between.
Heat 2 tablespoons of oil in a frying pan. Fry the sausages for about 10 minutes, turning them over. Peel onion and cut into cubes. Wash and clean the chillies. Cut 1 into very fine rings. Cut 2 pods in half and cut them several times.
Heat 1 tablespoon of oil in a saucepan. Fry the chopped chillies briefly in the oil. Set aside for garnishing. Sauté diced onions until transparent. Add 1 tablespoon curry and chilli rings and sauté briefly. Stir in tomatoes and ketchup.
Season to taste with vinegar, sugar and salt. Cut the sausages into slices and put them on skewers. Arrange sausage skewers, sauce and potato wedges on a plate. Dust with curry and garnish with chilli.