Preheat the oven to 200°C.
Peel the celeriac and cut into 8 equal sized pieces.
Heat an ovenproof saucepan and add a drizzle of olive oil and a knob of butter. Add the celeriac to the pan and cook until golden. Add a glass of water, season with salt and pepper then add the sprig of thyme and the crushed garlic clove. Transfer to the oven and cook for 45 minutes, check the dish often, adding a little water if necessary.
Heat a frying pan to very hot and then cook the foie gras for 1 minute on each side. Remove from the pan and place on a few sheets of kitchen paper. Season well. Remove the grease from the pan and re-heat. Add the deer steaks to the pan and cook for 2 minutes. Turn over and cook the other side for another two minutes. Remove from the heat and rest on a baking sheet.
Remove the grease from the pan again and then add a knob of butter. Add the lingonberries to the pan, cook for 2 minutes then deglaze with the red wine. Add the chestnuts and then reduce the liquid to a syrup. Transfer the deer steaks to the oven and cook for 6 to 8 minutes. One minute before the end of the cooking time, place a foie gras slice on top of each steak and heat through for the final minute.
Cut the cooked celeriac into slices and then arrange on large dinner plates. Place a deer steak on top of the celeriac, top with a slice of foie gras and then drizzle the lingonberry sauce over the dish to serve.
«Taste the syrup before serving - if it is too tart, add a teaspoon of sugar to sweeten.»