Drain all but two tablespoons of oil and return the pan to the heat. Add lemon slices and cook, turning once until they are browned. Add 1 tablespoon lemon juice and stir. Continue stirring while you add butter, one tablespoon at a time to the pan. Just before the first pat of butter is completely melted, add the next pat. Continue in this manner until the butter is used and you have a sauce. Stir in the parsley and pinch of oregano.