Whisk together the flour, cornstarch, sugar, sea salt, and baking powder in a medium bowl. Keep a tablespoon of this mixture aside to toss the strawberries in later.
In a large bowl, combine the eggs, buttermilk, oil, and vanilla.
Add the dry ingredients (excluding the tablespoon you kept for the strawberries) to the wet ingredients, and mix only until combined. Be careful not to overmix.
In a small bowl, toss the strawberries with the reserved tablespoon of dry ingredients. Make sure all the strawberries are coated.
Fold the strawberries into the waffle batter using a spatula.
Heat the waffle iron, and grease well with oil or nonstick cooking spray. Pour in ⅓ cup of batter (adjust the amount based on your waffle maker) and cook according to the manufacturer's directions, until your waffles are golden brown. Mine took 5 minutes.
Notes
Gluten-free: Use 1-to-1 flour blend that contains xanthan gum. 2¼ (333g) of Bob's Red Mill 1-to-1 gluten-free flour made delicious waffles!Dairy-free: Use 1¾ cup (420ml) non-dairy milk, take out 5 teaspoons (25ml) of milk and replace with 5 teaspoons apple cider vinegar.