Peel and wash the potatoes. Place in a large pan of salted water and bring to the boil - cook for 10 minutes from boiling point.
Peel and finely dice the shallots. Finely chop the chives. Season the calves liver slices with salt.
Heat a frying pan, add olive oil and sear the liver slices for 2 minutes on each side. Remove from the pan and set aside.
Add a knob of butter to the same pan, along with the shallots. Cook for 1 minute and then return the foie gras to the pan and deglaze with 3 tablespoons of water and the balsamic vinegar.
Drain the potatoes and then crush with 80g butter and add the chopped chives.
Use stainless steel serving rings to plate the potatoes. Serve the liver alongside the potatoes and finish with a drizzle of sauce.
«Add a spoonful of tomato puree to the sauce to bring together. Use the tip of a knife to test when the potatoes are cooked.»