Cook raisins in a little water for 10 minutes. Drain and cool. Mix together brown sugar, butter, oatmeal, baking soda, and flour; put in bottom of a 9-x13-inch cake pan (reserve some oatmeal mixture for topping). Mix together egg yolks, sugar, sour cream, and cornstarch. Boil until thick, stirring constantly. Add raisins and vanilla. Pour over bottom crust and sprinkle remainder of oatmeal mixture on top. Bake at 350 degrees for 30 minutes or until done.