I think liver and mashed potatoes is always good in combination. I decided to prepare topinambur puree, but I also added purple potatoes because of the starch content. To give the dish a fruity note I poached slices of a pear in cognac, flavoured with balsamico.
150 g topinambur
150 g potatoes
100 ml heavy cream
Peel topinambur and potatoes and cut in cubes. Cook both in boiling water but in two different pots. Mash both and add to the warm heavy cream. Season with salt and pepper. I served beef liver together with the puree, that I fried in butter flavoured with sage.