Preheat waffle iron to medium-high. Process blueberry kefir, whole-wheat flour, all-purpose flour, eggs, canola oil, cornstarch, baking powder, vanilla, and kosher salt in a blender, or whisk together in a bowl until smooth. Fold dried blueberries into batter.
Brush waffle iron with oil. Pour batter into waffle iron according to manufacturer's instructions, and cook until brown and crisp. Repeat with remaining batter. Serve immediately, or let cool and freeze in a zip-top freezer bag up to 2 months. Reheat waffles in a toaster until crisp. Garnish waffles with fresh blueberries, optional.