Rhubarb Custard Pie

2 c. chopped rhubarb
2 egg yolks
1 c. sugar
1 Tbsp. flour
4 Tbsp. water
1 tsp. vanilla

Cover rhubarb with hot water, let stand five minutes; drain. Beat egg yolks, sugar, flour and water. Mix in rhubarb and boil until tender, stirring consistently. When thick, add vanilla. Pour into baked pie shell. Beat two egg whites until stiff, fold in 1/2 c. sugar and bake until browned.