Heat the oil in a large saucepan. Add the onion, bacon and kumara. Saute 4-5 minutes or until the bacon is browned and the onion is transparent. Add the water and simmer gently for 15-20 minutes or until the kumara is softened. Mash with a potato masher to break up the kumara pieces. Add the milk and mint. Gently reheat until warmed through.
Serves 4-5.