Beat eggs well; add milk and vanilla.
In a separate bowl, combine rice flour, tapioca starch, potato starch, sugar, and salt. Add to egg mixture and whisk until smooth.
In a saucepan over medium heat, combine the blueberries, ¼ cup water, orange juice, and sugar. Stir gently, and bring to a boil. In a cup or small bowl, mix together the cornstarch and ¼ cup cold water. Gently stir the cornstarch mixture into the blueberries so as not to mash the berries.