Cut the potatoes into 1 cm thick slices, keeping the slices of the potato together.
Use a sharp round cutter to cut the middle from the potato slices (the round cutter needs to be big enough for the sausage to fit through).
For each potato, place a sausage through the middle of the cut potato rings.
Place on a baking tray and seperate the potato rings around the sausage (see picture). Drizzle with olive oil, salt and pepper. Bake for 40 minutes, turning half way through and baking until the potatoes are crispy and cooked through.
Serve the potato-sausage-hot-dog with crispy onions, tomato sauce and mustard.