These, like salmon sandwiches, are made from materials usually in every household, and can be made at a moment's notice. Stir the oil into the egg, add a few drops of vinegar or lemon juice. Remove the sardines from the oil, take off the tails and heads and remove the bones. Mash them in a bowl, add a tablespoonful of vinegar, or the same amount of lemon juice. If you have lettuce or cress, either shred it, or put one leaf between the fish and the buttered bread.