This is the way my mother would serve mashed potatoes.And we always cleared up the plate and so does my daughter,who won't touch mashed potatoes otherwise. No quantities listed here,use as much as you wish.

Ingredients:
onions,chopped,as many as you wish
salt,pepper
tomato paste
oil

Heat up the oil in a frying pan.
When browned add tomato paste and stir until incorporated.
Season with salt and pepper and use to top mashed potatoes.
It can be tried also without the tomato paste.