Combine whole eggs, yolks, milk and sugar in a double boiler, stirring continously. When the mixture becomes syrupy and well blended, add the potato and vanilla extract, mixing well, until mixture holds together and starts to separate from the pan. Cool, and refrigerate for 1 hour for easier handling.
To make the caramel coating, combine the sugar, water and cream of tartar in a saucepan, and heat over medium heat. Continue stirring until the syrup turns golden brown (caramel) about 8-10 minutes. Keep it warm over a very low heat.
Shape the egg mixture into a small ball or candy shape. Using a toothpick or a pair of tongs, dip into the hot syrup, swirling to coat evenly. Place into a greased pan and let it cool. Wrap each candies in colored cellophane if desired, or serve in a serving platter.
