|Preheat oven to 350°. Lightly grease and flour a 9x13 inch baking dish.|
In a large bowl, combine flour, salt, soda and sugar. Make a well in the center and add eggs, oil and vanilla. Mix well.
Fold in diced apples and walnuts, if desired.
Spread into prepared dish; bake for 40-50 minutes. Cake is done when toothpick inserted in center comes out clean.
When cake is done, punch holes in it with a toothpick and pour caramel sauce over hot cake.
For Caramel Sauce, heat all ingredients together over medium heat. Bring to a boil, stirring constantly. Let boil for about 2 minutes. Pour over warm cake.