Potatoes
chopped onion
carrot diced and cooked
olive oil
salt and pepper
vinegar
mayonaise
Boil potato with a little salt and peel in running water. Put it in a big mixing bowl and mash. Add all other ingredients and mix well.
Optional: Add canned sweet corn or thinly sliced cucumber (add salt and squeeze out the juice). In Japan, you can get the "Magic Salt" in supermarkets. I found it years ago and is still using it. It's a bit expensive, though.
decorate with mini tomato before serving.