Combine 3/4 cup sugar and corn starch in medium sauce. Stir in rhubarb. Cook and stir over medium heat until mixture comes to a boil and thickens. Cool and set aside. Stir together milk and vinegar and set aside. Combine flour and remaining 3/4 cup sugar. Cut in butter until mixture is crumbly and set 1/2 cup of mixture aside. To remainder add baking powder, baking soda and nuts. Combine egg and milk mixture and add to dry ingredients, stir until just moistened. Spread 2/3 of the batter over the bottom and sides of a buttered 9" spring form pan. Spoon rhubarb filling over batter. Drop remaining batter over rhubarb by spoonful, sprinkle with reserved streussel mixture. Bake in preheated 350 F oven 50 minutes.