Don't bother peeling the apples unless their skins are really unattractive. Cut up 3 or 4 of them, until you get about 2-1/2 or 3 cups of chopped apples. Sprinkle the lemon juice over the apples. The acid in the lemon juice prevents the apples from turning brown. The raisins will taste best if you plump them first. Do this by measuring them into a cereal bowl and adding enough warm tap water to cover them completely. Allow them to sit for a few minutes, absorbing the water, and softening up. Drain them very well when you need them. I actually squeeze them to make sure they are very dry. Chop up the celery, it should take about 2 stalks or so. I add black walnuts because I get them for free, but you can use regular walnuts or omit them completely if you don't have any handy. Mix everything together in a medium sized bowl with the mayonnaise and sugar, coating all of the ingredients with the mayonnaise. It is now ready to serve, or you can chill it overnight and serve it tomorrow instead. This is so crunchy and chewy, it is perfect contrast for a meal which is soft, or easy to chew. This recipe serves 6.