The broth left over from boiling potatoes retains its delicious flavor. How about making this when you've made potato salad?
It's often said that vitamin C from potatoes are strong against heat. I felt that throwing away the broth was a waste, so I made soup out of it. I always make this on any day I make potato salad.
You can mince vegetables such as onion, carrot, cabbage - whatever you like - and add to the soup as well.
Enjoy Japanese food around the world.