Heat a large, preferably cast-iron, pan over medium heat. Remove the casings from the ring bologna and slice on the diagonal 1/2 inch thick. When the pan is hot, add a lump of butter and a spoonful of olive oil, and then add the bologna in one layer, leaving some space between the pieces. Fry until dark pink crusty edges form on both sides. Remove from the pan, keep warm and continue frying the rest of bologna.