Preheat the oven 350 degrees. In a 1-quart non-stick skillet over medium-high heat, add ¾ cup sugar and stir until it melts and is light brown. Pour into a 9 x 2 round cake pan and swirl the pan carefully to distribute the sugar evenly on the bottom and sides. In a blender, place the eggs, egg white, evaporated milk, sweetened condensed milk, and salt. Blend on High until the mixture is smooth and all of the ingredients are well incorporated. Pour the mixture into the cake pan. Place the pan inside a glass baking dish filled halfway with warm water. Transfer to the oven and bake for 40 to 50 minutes or until a knife inserted in the center comes out clean and does not giggle. Remove the cake pan from the water and let cool for 30 minutes. Place in the refrigerator and leave for 90 minutes. Meanwhile, in small bowl, mix the sour cream, milk, 2 tablespoons sugar, and vanilla extract. Stir until the mixture is smooth and has a light consistency. To unmold the flan run a knife around the edge of the cake pan. Place a platter on top of the pan and carefully turn over. To serve slice, plate, and drizzle with the sour cream mixture.