In a separate large bowl, whisk together flours and salt. Pour the milk and egg mixture into the flour mixture. Mix until incorporated. Dough will be wet and shaggy. Leave dough in the bowl, cover with a dishtowel, and leave to rise in a warm area for at least an hour. After an hour, mix in the baking soda mixture to the risen dough. Let the dough rest while you heat the griddle.