For the mashed potatoes with chicken liver, peel the apple, clean and wash the liver. Finely dice the apple and liver, cover with 1 tablespoon of water and steam until soft.
Wash the potatoes and cook with the skin in steam until soft. Puree apple and liver with a blender. Peel potatoes and press through potato ricer. Mix with the apple-liver mixture. Add oil and mix well the mashed potatoes with chicken liver.