Mix yoghurt, salad cream and herbs. Season with salt, pepper and 1 pinch of sugar. Drain the cucumbers. Bring water to the boil, remove from the heat and heat the sausage in it for about 5 minutes.
Cut open the buns, put the sausage in. Add mustard, ketchup and tartar sauce. Cover with cucumber slices and sprinkle with roasted onions.