Preheat a waffle iron according to manufacturer's instructions.
Place the flour, sugar, baking powder, baking soda, and salt in a large bowl; stir to combine.
Add the eggs, vanilla and milk to the dry ingredients and stir to combine. Slowly add the butter, stirring constantly.
Coat the waffle iron plates with cooking spray and cook the waffles according to manufacturer's directions.
While the waffles are cooking, make the sauce.
Place the strawberries, sugar and cornstarch in a pan over medium heat. Cook, stirring occasionally, until berries are soft and sugar has dissolved, about 10 minutes.
Spoon the strawberry sauce over the waffles. Top with whipped cream and serve, garnished with mint sprigs if desired.