Lightly season the venison then heat a frying pan over a medium flame and add a little sunflower oil.
Sauté the meat in the oil until brown all over then reduce the heat slightly and add the 20g of butter and roll the meat in the butter and oil mixture. Let the meat cook to medium rare (the venison will be dry and tough if overcooked) taking care not to burn the pan. this should take 2 minutes on each side.
When the meat is cooked, remove it from the pan and set it onto a warm plate to rest.