Combine oil and sugar, and stir in sourdough starter. Mix in eggs, one at a time, beating well after each. Fold in pineapple, carrots, walnuts, coconut and vanilla.
In a separate bowl, combine flour, cinnamon, salt and baking soda. Add dry ingredients to wet ingredients, stirring just to combine.
Spoon batter into greased and floured 9 x 13-inch pan. Bake in a preheated 350°F oven for 45 minutes, or until cake tests done. Remove cake from oven and cool completely on a wire rack before frosting.
1/4 to 1/2 cup (1/2 to 1 stick) butter, at room temperature 8 ounces cream cheese, softened 1 teaspoon vanilla 3 1/2 cups (1 pound) confectioners' sugar 1 cup chopped nuts 1/2 cup minced candied ginger, or 1 teaspoon ground ginger (optional) milk
Combine butter, cream cheese and vanilla; beat until light and fluffy. Add sugar gradually, beating well. Stir in nuts and/or ginger (if desired). Add milk, a little at a time, until frosting is a spreadable consistency.