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.
Wash potatoes, cut in half, and place in saucepan of cold water. Cook, covered, over medium heat for 25 to 30 minutes or until tender.
Drain and dice potatoes when cool.
Add vegetables and egg to potatoes, and toss.